Delft Science in Design 2 - Research in Design Series

Research in Design Series Volume 3 ISSN 1569-7258

Previously published Volume 2. E. van de Kar and A. Verbraeck, Designing Mobile Service Systems Volume 1. R. Binnekamp, L.A. van Gunsteren and P.-P. van Loon, Open Design, a Stakeholder-oriented Approach in Architecture, Urban Planning, and Project Management

CONFERENCE PROCEEDINGS

4 APRIL 2007

Edited by Mick Eekhout, Tetsuo Tomiyama

IOS PRESS

© 2008 IOS Press and the authors. All rights reserved All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, without prior permission from the publisher. Published and distributed by IOS Press under the imprint Delft University Press PRINTED IN THE NETHERLANDS Publisher & Distributor IOS Press Nieuwe Hemweg 6b 1013 BG Amsterdam Netherlands fax: +31-20-687 0019 email: [email protected] www.iospress.nl www.dupress.nl Legal Notice The publisher is not responsible for the use which might be made of the following information ISBN 978-1-58603-739-0 Editors Mick Eekhout, Tetsuo Tomiyama Layout Manuela Schilberg Review Committee Adriaan Beukers Mick Eekhout Piet van Genderen Norbert Roozenburg Pieter Swinkels Tetsuo Tomiyama Jan Vambersky

Delft Science in Design 2 M. Eekhout et al. (Eds.) IOS Press, 2008 © 2008 IOS Press and the authors. All rights reserved.

Preface Delft Science in Design 2 The Architecture Faculty is a highly appreciated, self-willed and essential part of TU Delft. With its design tradition the Architecture Faculty, together with Industrial Design Engineering, takes up a special place within our Delft University of Technology. It is characteristic of both Faculties that they utilise the developments in both science and the art world. Not only do they improve everyday products - for instance a house or the heel of a women’s shoe - but because of their creative designs they also add value to these products. An issue is that the outside world tends to classify design studies as not being truly scientific. This often makes it more difficult to obtain extra funding for research, and the education is not always given its real merit by the evaluation committees of the Ministry. I feel this is unjustified: to me, architecture and industrial design engineering are academic studies in the same way that applied physics or electrical engineering are academic studies. I do think, however, that the formulation of theories with regard to academic design needs to be further developed. For this reason this aspect has received increased attention within the Delft University in recent years.

Academic design At first glance an architect will design something differently from a chemical technologist, for instance. To be able to compare the academic level of both professional areas irrespective of these different angles, criteria have been formulated that an academic designer must comply with. To this effect Anthonie Meijers, Professor of Philosophy and Ethics of Technology at TU Eindhoven and TU Delft, interviewed representatives from different technical fields. Based on these interviews he concluded that the architect and the chemical technologist share a common design framework. For instance, he noted that all groups of academic designers will first redefine the problems before they start to look for a solution. They are all able to design at system level and with a high degree of complexity. It also became clear that matter-of-factness is an important characteristic that all engineers share. Both architects and chemical technologists are able to cope well with risks and changes to the definition of the problem in the course of the design process. Based on these findings the three Universities of Technology in The Netherlands have formulated criteria with respect to the skills an academic designer must possess when he or she graduates from a University of Technology. For instance, engineers must have no difficulty

with abstract thinking and with taking certain liberties in their designs. They must also be able to re-formulate poorly structured design problems in order to arrive at a better solution.

Design Language In addition to these criteria I also feel it is essential that designers are prepared to look at their own design process. In doing so it is important that they are able to distinguish between the context of discovery and the context of justification. In the context of discovery one describes how a certain design was created. However, I feel this alone is not enough. In the context of justification one reconstructs or analyses the decisions made during the design process, and then proceeds to justify these decisions. This approach makes it possible to come to a critical exchange of ideas about the academic level of a design. At the same time this process can remove a lot of the perceived mystery that tends to surround the design process. In order to facilitate a constructive debate about, for instance, the context of justification, it is important that the different parties involved speak the same language. I am therefore a proponent of the development of a ‘design language’. Louis Bucciarelli is a professor at the Massachusetts Institute of Technology (MIT) and was a guest lecturer at TU Delft some years ago. He too was an enthusiastic supporter of the idea of a design language. Bucciarelli concluded that, like science, the design process has also changed considerably in the last few decades. The design process has evolved from the application of fairly simple, traditional experiential knowledge to the use of advanced technology. According to Bucciarelli, design has now become a social process: it is a multi-disciplinary collaboration between different specialists. Increasing numbers of specialists collaborate on the design of a building or product. In order to develop a good product an exchange of knowledge, negotiation and an understanding of each other’s wishes is essential - especially because, according to Bucciarelli, each party focuses on safeguarding the criteria of his own discipline within a design. In aircraft design strength is the focal point for a structural engineer, and speed comes second. An engineer who is responsible for propulsion, in contrast, will focus mainly on the engines and not so much on the structure. In a building process we can see a similar division. An architect wants to realise a high-profile design of the building as an object in the built environment; politicians seek to use the building as a means with which to impress the public; the structural engineer wants the design to be stable and structurally sound; the project developer wants the building mainly to be profitable for a

long time. They all will mainly look at the same building from the perspective of their own interests. A common design language could contribute to increasing the transparency of the discussion between these parties. Bucciarelli suggests that each discipline should compile a terminology list that is relevant to the professional field in question. In the list terms must be ranked in order of importance. Based on these terminology lists it would then be possible to devise a design language. It would, however, be essential to the development of this language that each party acknowledges the expertise of the other parties, and accepts their proposed terms. If this kind of acceptance is not realised consensus will never be achieved. And bearing in mind the strong-willed types of people usually involved in the design process, this will not be a simple task.

Composer I feel that the development of a design language is a challenge par excellence for engineers of Delft University of Technology. We are able to analyse problems matter-of-factly, but enjoy finding inventive and creative solutions. There may be architects who fear that a design language will restrict their creativity, but I don’t think such fears are justified. Musical notation has never inhibited the creativity of composers. Quite the contrary: such notation allows composers to discuss their ideas with other composers and make it clear to musicians how the music must be played. I expect that a design language will fulfil a similar function, and that it will contribute to creative and academic designs that can be discussed in debates that push back frontiers and open up new horizons.

Prof. Jacob T. Fokkema Rector Magnificus, Delft University of Technology

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Contents Jacob Fokkema Preface

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Piet van Genderen Introduction

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Design Products Sotiris Koussios, Adriaan Beukers Aircraft Fuselage Design in the Century Ahead A Multidisciplinary Approach

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Jan Jacobs Application of New Technology as a Starting Point in Industrial Design

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Mick Eekhout, Ronald Visser Blob-Shells: Composite Stressed Skin Roofs for Liquid Design Architecture

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Joris Melkert Design in the Chair AeroSpace for Sustainable Engineering and Technology (ASSET)

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Hans Hopman Innovation-Focused Ship Design Developments and Options from a European Perspective

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Ulrich Knaack Integrated Design Integrated Design in Architecture – and what comes next?

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Arie Romeijn, Jan Meek Offshore Structures: Hidden Treasures for Designers

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Han Brezet, Satish Beella Soft Mobility Products The Experiences of the Delft Design Institute

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Design Processes Frederik W. Jansen, Date W.E. Rentama AI Techniques for Conceptual Design

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Hugo Priemus Construction Safety: At the Crossroads of Building and Design The Case of the Multifunctional Bos & Lommerplein Estate, Amsterdam

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Guus Berkhout Design as an Integral Part of the Innovation Process

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Margot Weijnen, Paulien Herder, Ivo Bouwmans Designing Complex Systems A Contradiction in Terms

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Hennes de Ridder LIVING BUILDING Environment for Sustainable Development in a fast Changing World

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Jürgen Rosemann Research by Design in Urbanism

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Mick Eekhout Epilogue

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Introduction The series of congresses Delft Science in Design was initiated in 2005 by the so-called “Platform Design” of our university. The mission of this platform includes promoting and advancing the exchange of lessons-learned on design (as an activity of the scientific staff of the university) between members of staff of the university and between members of staff and industry. Also, the platform has been tasked to amplify the visibility of the results of academic effort in design at our university. The congresses serve these purposes. The Platform Design is suggesting that many members of scientific staff design experiments, processes, “things”, etc without recognizing them as design effort as such. Considering it this way, the majority of the TU Delft community is directly or indirectly involved in design activities, as are many of our graduates. The questions “what is design”, “what is engineering”, “what is science” can fiercely be debated. We understand that the difference cannot easily be measured: Between the extremes of artistic design and pure science the transitions are like in fluid: they are smooth and gradual. Maybe an approach focussing on how the university deals with knowledge provides a better entry to the debate. Many elements of knowledge can be readily transferred between peers (that is, between scientists / engineers at the same level of professionalism in the same field of science). In this case codified knowledge is a legitimate measure of output and performance. But frequently knowledge cannot be easily codified or is tacit. In such cases it is far more difficult to provide a yardstick to measure a group’s or a person’s performance. Objectification of performance by peer assessment might be the way out for the management of the university. The Platform Design is contributing, and will continue to contribute, to finding a fair solution. Another very important consequence of the issue of appreciation of uncodified or tacit knowledge is that the mutual understanding between scientists from different disciplines may get lost. It is one of the two major objectives of the Delft Science in Design congress: offer a kaleidoscope of the activities of our various faculties to all university colleagues and students in order that staff and students can be made aware of activities in other laboratories and have the opportunity to be informed on details. Being informed is the first step to understanding. By doing so, another personal benefit can be served as well: more often than not, activities in other sciences, once properly understood, may stimulate new ideas, approaches and solutions in the own science. The second objective of the congress is reflected in the metaphor proposed by the chairman of the congress, Mick Eekhout: “Design is the tunnel through which the results of scientific research are brought to society”. The congress offers a variety of oral papers and poster-stands in 11

interactive sessions. In particular the latter facilitate direct contacts between scientists and delegates during the congress. Many activities on conversion of scientific novelties into products or processes for commercial or governmental benefit start up from Small and Medium size Enterprises (SME’s, in Dutch: MKB). Of course, large non-academic research institutes also have this ambition to create a roadmap for return on investment, but not at the level of direct transfer. For the purpose of supporting this “tunnel to society” the Chairman of MKB-Nederland, Mr. Loek Hermans, has delivered a keynote address in the congress. Entrepreneurs in SME’s have been invited to join our congress and exchange views on opportunities with the authors of oral papers and interactive papers. Support on how to establish a joint project, how to deal with intellectual property etc. will be available in the interactive session area. We hope that the “tunnel to society” will not be one-way traffic, but that profitable contacts for both university and companies can be established. Today’s bouquet of lectures and posters is an arbitrary selection of TU Delft designers who have more or less worked in their design portfolio in multidisciplinary teams with remarkable results. The first series was quite material directed, this second issue of the Delft Science in Design Congress turned out to be more directed towards immaterial products and processes. In totality this book contains 14 articles, organized in one block on Design of Products and one block on Design of Processes. In the congress however, the day was organised in 4 blocks. Each block of 3 or 4 lectures in the program was followed by a short discussion, supervised by a moderator whose function was to stimulate the discussion on methodology and results and the common and specific topics between the different presentations. The lectures were deliberately mixed as to their professional background in order to obtain an interdisciplinary view on TU Delft. The posters in the lunch area were presented with the aim of extensive discussion with the authors. The posters have been included in the first edition of the congress book, but were left out in this final peer-reviewed version of the final edition of Delft Science in Design 2. We trust that the congress was inspiring and that it offered every participant shared benefits together with colleagues and entrepreneurs. We gladly solicit your feedback and active contribution to further advance the understanding and appreciation of design in our academic community.

Prof. Piet van Genderen Chairman of the TU Delft ‘Platform Design’ 12

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Delft Science in Design 2 M. Eekhout et al. (Eds.) IOS Press, 2008 © 2008 IOS Press and the authors. All rights reserved.

Aircraft Fuselage Design in the Century Ahead A Multidisciplinary Approach Sotiris Koussios1, Adriaan Beukers2 1

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Assistant Professor, Delft University of Technology, Faculty of Aerospace Engineering, Delft, The Netherlands Professor, Delft University of Technology, Faculty of Aerospace Engineering, Delft, The Netherlands

Abstract As the development of conventional aircraft has reached a point of saturation, novel configurations are required for coping with increased operational demands for airliners and stringent environmental requirements for the future. In the search for such configurations, old ideas like the Blended wing Body (BWB) seem to readily provide attractive solutions. However, for successful application of the BWB configuration, a major problem must be solved: the design of a rotationally non-symmetric fuselage with a reasonable weight. This paper outlines the search for the optimal fuselage. Beginning with a short historical overview and a presentation of future demands, the concept of multidisciplinary design, together with simple design rules, is enabled for crystallising the optimal anisotropic multi bubble fuselage arrangement. Keywords: Blended Wing Body (BWB), Multidisciplinary design, Fuselage

1. Introduction The relatively short history of aviation provides several examples where the success of a particular idea (usually reflecting on aircraft configurations), although technologically feasible, failed on technical and / or economical reasons [2, 4]. After a switch from wood and fabric to fully stressed aluminium shells, the appearance of conventional airliners has not changed sine the end of the 60’s [10]. By considering the typical lifecycle curve of technological products and by taking the latest improvements in account (which did not lead to spectacular improvement of structural performance), the conclusion can be drawn that the assessment of alternative aircraft configurations is worth looking at [3, 5]. With the accelerating expansion of air travelling and the increasing economical and environmental requirements, failures of the past become nowadays interesting candidates. In particular, concepts like the flying wing and the blended wing body appear again as possible solutions. As compared to the past, the difference that can enable their success relies on a totally

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different economic / environmental framework and the advanced technologies that are available [16]. The a-priori selection of a suitable configuration for future aircraft is a dangerous task. Without a complete comparative investigation that provides a reliable picture of mainly structural and economic performance, it is difficult to select an aircraft set up with absolute confidentiality. However, with some design tools like the structural efficiency of basic geometry / load arrangements and performance data from the literature [10-13, 16], a particular direction can already be determined. Several studies performed by Boeing and NASA indicate the outstanding performance of Blended Wing Bodies. These configurations reflect on a mixture of conventional (tube – wing) aircraft and the flying wing, as invented around 70 years ago. Despite its favourable performance, the Blended Wing Body imposes some significant structural problems, particularly in regard to the fuselage. The outer geometry does not permit for rotational symmetry; therefore the weight will definitely increase as compared to conventional aircraft fuselages [8, 11-13, 17]. However, with clever pressurised element arrangements and strategic use of the anisotropy provided by the utilised materials, feasible solutions can be found [4]. This paper outlines the search for the optimal fuselage. Beginning with a short overview of aviation history, several benchmark designs are identified. The classic airliner design is accordingly presented as a result of a long development trajectory and its suitability for future demands is tested against stringent environmental requirements. As the development of conventional airliners has already reached the consolidation phase, in section 3 the need for innovative configurations is motivated and the Blended Wing Body is presented as a feasible solution. In addition, the problem of designing a satisfactory BWB fuselage is outlined. In section 4 the principle of multidisciplinary design is explained in relation to the new fuselage. The main goal formulated here is the integration of various functions into a single design. With the aid of basic design rules and geometric simplifications we explain in section 5 why the multi-bubble option is the preferred solution. As a major condition, a membrane stress state for the fuselage panels is here introduced. The membrane stresses are further explained in section 6 where the principle of tailoring material anisotropy to the bubble geometry is outlined. After a short performance assessment, the paper ends with some concluding remarks, warnings and recommendations.

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2. Framework In this section we will try to place the central question of this paper (fuselages in the century ahead) in an historical and future perspective. On one hand we can learn from the past by identifying major breakthroughs, and on the other hand we can attempt to predict which aerostructure properties are the “hottest” given the economical climate of today and the environmental demands of tomorrow. 2.1 A brief history After the first motorised flight, performed by Wilbur and Orville Wright in 1903, aviation has shown an exponential growth both in terms of technological sophistication and economic impact. To illustrate this, one must realise that the wingspan of a Boeing 747 is bigger than the first powered flight [4]. From a macroscopic point of view, this development looks rather smooth and continuous; however, particular breakthroughs are truly responsible for this success story. While the first aircraft was mainly based on the combination of a wooden frame and fabric, the introduction of industrially produced all-aluminium stressed skin aircraft in 1932 (Boeing 247, DC2, DC3) initiated the scientific approach of evaluating aerostructures. The isotropic character of such materials paved the way for predicting and reliably dimensioning structural parts like wings and fuselage. As increased flight heights (coupled to increased velocity levels) proved more economical, designers had to face the challenge of providing a liveable passenger environment in terms of acceptable cabin pressure. One of the first pressurised cabin structures can be found in the Boeing 307 “Stratoliner” (1937). At the same time, the introduction of jet propulsion at the end of the Second World War finally broke the barrier of performing over seas flights within acceptable time. The pressurised cabin concept however, dramatically forced novel developments in the area of fuselage design. Until a series of dramatic accidents with the Comet of The Havilland, nobody was aware of phenomena like fatigue and crack forming. With Boeing and McDonnell Douglas being the first companies that successfully solved this problem with respectively the introduction of the 707 and DC8, a fascinating cycle of aircraft structures development is crystallised in the form of the typical passenger carrier as we know today: a cylindrical tube (optimal for internal pressurisation) with wings, a horizontal tail section and a rudder. With the typical passenger carrier configuration entering our skies from the end of the sixties the only variation can be found in the number and position of engines and the number of decks. The 747 with a partially double deck is probably the biggest revolution in aviation history making overseas flights affordable for the “average” people. On the other hand, developments like the Concorde did not realise a breakthrough due to

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their disappointing economic performance (despite their extraordinary level of technology). 2.2 Future demands: economics In a growing competitive environment, aviation economics are nowadays the decisive factor for the success of both manufacturers and operators. For an airliner, customer preference can be assured by either offering better services or lower prices. The first method, better services, would in first instance mean shorter travelling times followed by more comfort, better customer service etc. Shortening the travelling time however, does not seem to be that important for potential customers [2, 4]. A flight from London to New York could last 4 hours instead of 7 but when considering the time for checking, boarding and arriving at the airport, such an improvement is only marginal. Passengers are not prepared to pay several times the average ticket price for saving a few hours. This is the reason for the unsuccessful story of the Concorde. We should mention here that reducing the flight time through supersonic velocities with a marginal increase in the ticket price is not feasible due to aerodynamic constraints [5]; the drag increase is disproportional. Hence, subsonic flights will be there for the next decades. To demonstrate the effect of travelling speed on the fuel efficiency we provide here in table 1 some typical results [5].The second method for attracting flying customers relies on the ticket price reduction. With the introduction of the so-called price fighters however, the margins for competition are narrowing. In figure 1, the trends in cost and revenue for passenger transport are given [5]. Although not completely up to date, the figure typically demonstrates the declining profit per passenger seat.

Fig. 1. Trends in cost and revenue of passenger transport

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Table 1. Transport systems and their fuel efficiency

The highlighted tendency can partially be assigned to the market mechanism. However, a decisive parameter for this development is the possibility for profit as determined by current technologies. To increase profit, aircraft should be more economical. A primary factor to improve economics is the reduction of fuel consumption by means of better engine performance, advanced aerodynamics or weight reduction. In particular the latter is highlighted by several researchers as an important candidate [6, 10-13, 16]. However, some of them share the opinion that a weight reduction of even 30% will result in an operating costs reduction of only 5%. Assuming more realistic values (like 10%) the operating costs gain is very small. On the other hand, we should not forget that structural weight reduction is the only thinkable short term improvement.

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2.3 Environmental Goals in 2020 Having a rather ambitious character, the Strategic Research Agenda of ACARE (a European conglomeration of aerospace institutions, manufacturing companies, airports airliners etc) has formulated a set of requirements for a hypothetical medium sized airplane in the year 2020 [1, 9]. The main goal behind this set is the “greening” of aircraft. Points of special attention are: 1. CO2 reduction by 50% per passenger kilometre. The breakdown of this reduction is: 20-25% fuel consumption reduction due to structural aircraft improvement, 15-20% by engine improvement and 5-10% by operations optimisation. 2. 50% noise reduction as compared to the current average levels. This is mainly to be achieved by improved engines that are placed more strategically, shorter take off trajectories, less required power and improved operations. 3. 80% reduction of NOx emissions, to globally be achieved by the techniques described above. 4. Minimisation of industrial impact during manufacture, maintenance, overhaul, repair and disposal. Although not quantified, the achievement of this goal will depend for a large portion on political issues. According to Tenney and Pipes [16], such a rigorous reduction will probably imply a dramatic weight reduction. The question arising now focuses on the feasibility of current aircraft technology to meet this demand. To deploy a thorough judgement about the feasibility of these targets, we should keep in mind that aircraft structures as they exist now are the result of nearly 70 years development. During that time, little has changed when regarding airplane configurations at a very conceptual level. Current designs are still mainly based on fully stress aluminium skin concepts. Considering the technological life cycle of products in general, figure 2, one can distinguish four stages [3, 5]. The initial stage for airliners, the development, took place around the Second World War. From 1950 to 1975 an expansion can be observed, significantly aided by the development of jet engines. The technology reached the consolidation stage from roughly 1975 to 2000. From that point, little space for improvements can be found. The introduction of improved alloys in combination with the replacement of several secondary sub structures by composites (mainly applied in the empennage, control surfaces and high-lift devices) has only led to marginal improvements. In the 80’s the Airbus A320 was the first to exceed 10% weight utilisation of composites [16]. Fibre metal laminates like Glare are introduced as well (Airbus A380). Boeing however, is already intending to create full com-

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posite aircraft by discarding the fibre-metal laminate option. Considering these two philosophies however, their common divisor is the assumption of the traditional tube-wing configuration.

Fig. 2. Technological product life cycle, projected on typical passenger aircraft

3. Feasible solutions: the Blended Wing Body In this section, by blending an overview of the “state of the art” technologies with the impact a particular configuration can have on the structural performance of aircraft, an assessment is presented regarding potential candidates, able to deal with the intensified economic and environmental requirements. 3.1 Configuration From the previous section it becomes evident that meeting the “2020’ goals in an economic environment where the profit margin per passenger seat is declining will be a difficult task. By extrapolating from the past where improvements on the classical wing-tube concept have resulted into rather marginal improvements (in terms of weight reduction) and by placing this event in the light of the technological product life cycle, one can conclude that the time has arrived for an entirely novel concept. With the latter we mean: a rigorously different aircraft configuration. In regard to the (yet undefined) novel configuration, two questions arise immediately: is this desire for novelty really original and justified? And: why should this time be the right one for such an introduction? To answer the first question we mention here that aircraft designers have always been experimenting with novel configurations. In this sense the flying wing, the cylinder-wing or mixture of them (Blended Wing Body) have been conceptualised even before the Second World War. The first flying wing that flew is the Northrop YB 49 that entered the sky in 1948. Lack of

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advanced flight control techniques and absence of a sufficient technological or economical reason for their introduction has suppressed their development. The idea lost ground until 1988 with the introduction of the B2 spirit bomber (figure 3). Summarising, we must answer that the idea of introducing a “novel’ configuration definitely lacks originality. However, the time is indeed right for doing something new: we are on the top of the product lifecycle curve (S-curve) for passenger carriers in an increasingly competitive environment. Hence a breakthrough is probably justified.

Fig. 3. The B2 spirit bomber, a reintroduction of an old idea, but this time with feasible flight control characteristics.

To most suitable configuration for enhancing significant weight reduction is the so-called flying wing. The main reason for this selection is that a flying wing does not incorporate a tail section, which is known for parasitic drag generation [3]. At the same time, the wing itself is both loaded by weight (payload, fuel, structural weight) and aerodynamic forces. In the optimal scenario, these loads do cancel each other on such a way that there is no bending. This will definitely lead to the lighter solution. However, from a flight control and passenger accommodation point of view, a less pronounced configuration is preferable: the blended wing body which is, in simple terms, the mixture of the classical passenger airplane and the flying wing, figure 4.

Fig. 4. Blended Wing Body (middle) as compared to typical airliners

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According to [5] the change from a conventional 800 passenger carrier to a BWB will result in the following benefits: • 27% lower fuel consumption • 15% less take off weight • 12% lower empty weight • 27% lower required total thrust • 20% higher lift to drag ratio 3.2 The potential of novel technologies Independently of the aimed aircraft configuration, a study of Pipes and Tenney [16] provides some numbers regarding the individual weight reducing potential of modern technologies application. These numbers are given in table 2 for a typical 800 passenger carrier with subsonic cruise speed. Table 2. Possible aircraft weight reduction through application of cutting edge technology

The provided numbers set the BWB configuration in a more sceptical light. The performance gain through aerodynamics is bigger but the overall picture is counteracted by less favourable structural and control characteristics. For the propulsion, the numbers do hardly show any difference. The data presented here are extracted from a study performed in 1998. More

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recent studies show a more positive picture for the BWB [10-13]. As the general consensus clearly shows the BWB outperforming the conventional configuration, we will further focus on it. 3.2 Structural challenges: fuselage As already indicated in table 2, the structure and control systems of a BWB are areas where the weight reduction potential is limited. Focussing on the structural aspects, an important distinction must be made for the wing section and the fuselage. The wing section is expected to readily become lighter as the bending and twisting stresses will have a less profound character. The lift-induced forces are called to cancel weight over shorter distances as compared to conventional aircraft where in fact the fuselage is a cylinder that is carried by the wing section. With wingspans currently approaching 80 meters, these bending loads are impressive. At the same time, the BWB wing section will have significant height due to aerodynamic requirements and will provide space for a passenger cabin, figure 5. The increased height provides sufficient design space for creating proper moment of inertia to resist bending and twisting.

Fig. 5. Artist impression of a BWB cabin space

In regard to the fuselage section, there is a significant variety of load cases that have to be considered. However, the most critical for a rotationally non-symmetric configuration is the internal cabin pressurisation. Although in the order of 0.8 Bar the generated forces can be impressive. On an average access door this would mean a force in the order of 10.000 [Kg force]. It is known from mechanics of materials that the optimal pressurisable shape for isotropic materials is a sphere [8]. Although less optimal, the cylindrical tube, as nowadays applied in aircraft is a preferred solution: it provides usable cabin space and utilises at least 50% of the material strength, from a static point of view. However, we should mention here that the dimensioning a pressurised fuselage is mainly based on fatigue

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requirements. In figure 6, a simple comparison is presented regarding the performance of non-spherical pressure vessels [11-13].

Fig. 6. A non-cylindrical pressure vessel is subjected to high bending stresses

Even from this simple comparison it becomes evident that the creation of non-cylindrical fuselages will introduce significant structural problems. Several studies are published with various concepts for alleviating this non-optimality [11-13]. However, the general indication is that the performance of the cylindrical fuselage is superior, but when considering the complete picture of the aircraft (including better load distribution, improved aerodynamics etc) there is a good reason for this introduction [6, 10]. Despite the less-favourable pressurisation characteristics, the abandonment of the cylindrical fuselage idea creates enough space for an entire reconsideration of the aircraft fuselage design where the principle of functional integration becomes viable.

4. Multidisciplinary design philosophy In a generic consideration, a fuselage must in first instance provide a safe environment to travelling passengers. This demand implies structural integrity and proper internal atmospheric conditions. Secondary, the level of comfort must be acceptable in terms of noise, available space and accessibility. At the same time, the fuselage must be lightning strike resistant and suitable to withstand a broad range of atmospheric conditions. As an additional function, the fuselage provides space to various electronic, hydraulic and climate systems. This extensive collection of functionality can be tackled by two principles: integration or segregation of functions [2, 4]. An example of segregation is the conventional fuselage where the loads are carried by the skinstringer-frame combination and the insulation is provided by separate layers. Oppositely, integration would imply a load carrying insulator like a sandwich structure [17]. Without claiming that an integrated solution is

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always the lightest, several advantages can be found in this principle. To visualise this, in figure 7 we provide a schematic graph where the degree of integration is presented as a function of the number of fulfilled requirements [3, 5]. In other words, the horizontal axis tells us which requirements are fulfilled (the closed to the origin the more important) and the vertical axis represents the added value in terms of simultaneously fulfilling this number of requirements into one design (if you wish, a single subsystem).

Fig. 7. Degree of functions integration (vertical axis) as a function of the number of fulfilled requirements

The figure clearly indicates that metals, while certainly satisfying mechanical requirements, and satisfactory dealing with corrosion problems, they are not able to immediately cover the problem of thermal and noise insulation. For this purpose, additional materials (thus weight) are needed. At the same time, composites on their own (with composites we mean the classical matrix-fibre combination) are not able to provide acceptable lightning strike resistance characteristics but certainly already include insulating properties. As indicated on the vertical axes, a single piece production of a sufficiently thick but light composite panel that contains metallic fibres would fulfil the complete requirements set. In regard to weight, we should mention here for metallic structures that this is mainly dependent on the frame pitch versus skin thickness. Under a certain pitch, the structure is governed by the allowed material stress levels and the weight remains more or less constant. Above the critical pitch, the structure is dominated by stability issues; hence the skin thickness must increase. Therefore, the weight reduction of a greater frame pitch is partially cancelled by the required elevated skin thickness. Since stability problems are dominated by geometry (stiffness and moments of inertia) a

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panel configuration providing increased effective thickness by low weight would in this case be preferable. Such a configuration is the so-called sandwich structure where the relatively stiff outer skins are separated by a thick layer of a light material (for example a honeycomb core or foam [3, 17]). While allowing for the increased frame pitch, the core can fulfil the function of thermal and acoustical insulator. An additional asset of composite-based sandwich panels relies on their tailorability: the fibre orientation can be adapted to the local load situation. Combination of this principle with a proper design of the panel curvatures will increase the possibilities for weight reduction.

5. Design toolboxes After obtaining a general impression regarding the challenges and possible solution directions for non-cylindrical fuselage panels, it is time to gather some basic design selection mechanisms for motivating the introduction of the novel fuselage concept [2]. 5.1 Materials selection Table 3. Material selection parameters for simple load situations

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To assess material performance we assume here simple load situations [2], as given in table 3. Steel has an elasticity modulus equal to 210.000 [MPa] which is three times the modulus of aluminium alloys. On the other hand, the density of steel alloys is app. 7.8 [g/cm3] (aluminium: 2.8 [g/cm3]). Composites show moduli that are between steel and aluminium but their density is usually lower. With these coarse indications it is easy to deduce why wing panels are made of aluminium and why steel is better for landing gears (titanium alloys are here omitted). Returning to the role of the materials selection parameters for fuselage design, one can easily deduce that a preferable situation is the one where the internal pressure results in exclusively tensile loads (membrane approach). This is additionally motivated in section 3. In the case of having no other option, one should accept bending stresses. Considering the panel-like nature of fuselages, the challenge is now how to create maximised bending resistance with a minimised amount of material. Here the role of geometry becomes evident. 5.2 Geometric parameters for stiffened fuselage panels One of the most critical loading conditions for a flat fuselage panel is the combination of internal pressure-induced bending and externally induced compression. For an initial geometry selection, the so-called 2-D beam column analysis has been developed [11-13]. Here an equivalent flat sandwich panel is compressed into a 2-D schematisation as given in figure 8.

Fig. 8. 2-Shematisation of a surface panel with bending inertia

Without proceeding into the mathematical part of this concept, the idea is to locate the optimal distance of the two face sheets for simultaneously complying with stability and strength requirements. This is done by varying the (artificial) parameter d and the sheet thickness t. The parameter d is artificial because it can virtually represent any stiffened panel. The stringers are in the case “smeared” out onto an equivalent sandwich structure [6].

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To exclusively create membrane stresses, one has to provide double curvatures to every panel. For dealing with the absence of rotational symmetry, the structure should accordingly be forced in the non-circular shape by supporting, fixing or clamping several, strategically chosen points of the structure. With a proper dimensioning and fixation, the stresses can then be transformed into tensile ones so stability will not be an issue anymore. In theory, stiffening of such a panel is not required, therefore it represents the lightest possible solution (d = 0, t is dominated by tensile strength).

6. From spheres through cylinders to bubbles 6.1 Geometry A possible fuselage shape (regardless rotational symmetry) can be described in a particular curvature development in two directions, perpendicular to each other, figure 9 [8].

Fig. 9. A doubly curved panel element with curvatures Rm and Rp.

By applying a uniform pressure on the inner side of the plate, the stress ratio in the two curvature directions is given by:

For simplicity we assume here that the main curvature directions are perpendicular to each other. From this simple equation it becomes evident why a sphere is optimal for isotropic materials; the strength in both directions is the same and so is the curvature. In the case of a cylinder, the

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radius of curvature in one direction (in this case Rm) is infinite since it represents a straight line. According to equation (1), the stress ratio will become equal to 2 which is the typical value found in an extensive collection of textbooks. However, when utilising isotropic materials, only 50% of the available strength is utilised. This is the case for conventional aircraft fuselages: 50% of the available material resources is a-priori not utilised. In the case of composites, one can align the fibres running over the panel with the so-called principal stress direction. In the case of a cylinder this would be 54.7°. When both curvatures show finite values, the fibre orientation can be adjusted accordingly. This principle will lead to a truly optimal material distribution where the occurring stresses show everywhere equal magnitude. Hence, the adjustment of the geometry to stresses can possibly provide the key for reducing fuselage weight. To achieve the above mentioned optimality goal however, a major problem must be solved; pressure does not have a direction of preference and therefore is rotational symmetric. A BWB fuselage is not, hence the nonsymmetry of the pressure carrying panels must be created on an artificial way by mechanical forcing strategic points and edges to obtain a certain position that ensures the desired curvature distribution. This inevitably calls for the incorporation of rods, bars and other members. An impression of such a solution (in one direction), is given in figure 10.

Fig. 10. A pressure resisting membrane in an elliptical fuselage section

The inner, pressure resisting membranes are forced into the two-lobe shapes by the tensional forces of the rods running from the floor to the ceiling. The membranes are exclusively loaded on tension and the fibre orientation of the utilised composite material is adapted to the curvature distribution. Disturbing the rotational symmetry in two directions leads to a conglomeration of “soap bells” usually referred to as “multi-bubble arrangement, figure 11 [4]:

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Fig. 11. A multi bubble arrangement of pressurised elements

The fixation in space of the bubbles is controlled by their intersection areas and the external forces (rods). The shape of the bubbles is additionally controlled by the material anisotropy: one can flatten out or sharpen a bubble by accordingly steering the fibre orientation. 6.2 Materials The need for “bubbleness” steering and the desire not to waste any material (as in the case of a cylinder) sets composites in the place of ideal candidates. Maximum strength by a minimal use of material can be assured by adapting the fibre orientation to the curvature distribution. In addition, the supporting rods can be designed on such a way that they experience only tension. The latter will omit stability problems. Referring to figure 7, additional features like metallic fibres (lightning strike) and foam (insulation) will be needed. Furthermore, local reinforcements for structural attachments, rigid inclusions and openings will certainly be required as well. With the information given in table 3, the ideal fibres candidate would be carbon [maximised elasticity modulus over material density]. The matrix selection is dominated by physical requirements (temperature range, flammability, UV resistance etc) since it only contributes to the overall strength in a very limited way. An outer protective shell is still needed for aerodynamic reasons. This is the only segregating step in this approach. While the shape (internal space), load carrying capabilities and other properties (insulation, conductivity etc) are fully integrated, the aerodynamic function is separated: bubbles and streamlined surfaces do not show any similarities.

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6.3 Assessment NASA Langley researchers [11-13] have performed an extensive study assessing feasible fuselage arrangements for BWB configurations. Next to ribbed and sandwich panels (flat and vaulted) and dedicated brace configurations, the multi-bubble concept is found superior. However, the performance of the cylindrical fuselage was still the best. We should mention however, that the option of tailored anisotropy is not considered in their work. On the other hand, buckling loads were included whereas in the present paper this topic has totally been omitted. In conclusion, the multi bubble performance has been found to be approximately two times better than the rigid options. Extrapolation towards tailored anisotropic, doubly curved panels sets the ability for approaching or even improving the performance as compared to cylindrical fuselages.

7. Conclusions & recommendations In this paper we have presented possible fuselage configurations for future aircraft. Beginning with a brief historical review where several benchmarks in the development of aerostructures have been identified, the future demands in terms of economic requirements and environmental constraints have been outlined. With the S-curve based theory (representing the lifecycle of technological products), the inability of conventional aircraft to cope with modern requirements has been demonstrated. From the alternatives for modern aircraft, the Blended Wing Body configuration has been chosen as a potential candidate. After a short assessment of the positive impact modern technologies can have on the weight reduction of aircraft, a major structural challenge for Blended Wing Bodies has been identified in the form of the fuselage geometry. With the principle of multidisciplinary design philosophy and with the aid of some basic design rules and tools, the multi bubble arrangement is finally selected as the most promising option. The proposed arrangement involves a simultaneous determination of the overall geometry in terms of curvature development and fixation points, and a local adaptation of the utilised anisotropic materials to ensure minimal weight. With the Blended Wing Body, the absence of rotational symmetry for the fuselage induces some significant structural challenges. Resisting rotationally symmetric loads (like pressure) with a non-symmetric structure inevitably involves bending stresses. By application of sandwich plates or stiffened skin panels, this problem is partially solved. Moreover, in the case of sandwich panels, secondary functions like insulation (thermal and acoustic) are fulfilled as well, while other requirements like lightning strike protection do still require additional elements (e.g. metallic fibres). Nevertheless, the alleviation of bending stresses by adapted geometry is an issue of primary concern for controlling the weight. In this case, membrane 32

elements like a 1-D or 2-D arrangement of bubbles proved to perform significantly better. In addition, tailoring of the involved panel anisotropy in combination with a strategic choice of fixation points and cell overlap has shown the ability for increasing the design space while still keeping the weight on acceptable levels. However, an outer protective (aerodynamic) shell is still found to be necessary. The space between the pressure resistor (membrane) and the outer shell can in this case be filled by lightweight foam or honeycomb materials for providing the desired insulating properties. The intention of this paper is to only provide a general direction where possible solutions can be found. For a more reliable judgment of the proposed configurations, an extensive comparative analysis, based on various load cases, is required. Nevertheless, the authors believe that the multibubble arrangement in combination with tailored anisotropic properties shows great potential both in terms of structural performance as well as in terms of providing integrated design solutions.

References [1] Anonymous. CleanEra, a Development for the Future of Aerospace. Internal memorandum, Faculty of Aerospace Engineering, Delft University of Technology, Delft, 2007. [2] Beukers A, Hinte E van. Lightness: The inevitable renaissance of minimum energy structures. Amsterdam: 010 Publishers, 1998. [3] Beukers A, Tooren van MJL, Jong de Th. Multi-Disciplinary Philosophy for Aircraft Fuselages. Part I. Applied Composite Materials (2005) 12: 3-11. [4] Beukers A. Flying Lightness; Evolution towards Minimum energy Aircraft Structures. Amsterdam: 010 Publishers, 2005. [5] Beukers A. Tooren van MJL, Vermeeren C. Aircraft Structures in the Century Ahead. Aeronautical Journal (2003) 107 (1072): 343-357. [6] Bradley K.R. A Sizing Methodology for the Conceptual Design of BlendedWing-Body Transports. NASA/CR-2004-0213016. [7] Koussios S. Filament Winding: a Unified Approach. PhD thesis report. Design and Production of composite Structures Group, Faculty of Aerospace Engineering, Delft University of Technology. Delft, December 2004. [8] Koussios S. Composing Composites: a Paradigm of Reversed Design. Proceedings of the Delft Science in Design Congress. Delft, The Netherlands, May 2005. [9] Lol JJ. Dutch Dreams. Article in: Aviation Week & Space technology, February 12, 2007. [10] Mohaghegh M. Evolution of Structures Design Philosophy and Criteria. AIAA 2004-1785. AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics & Materials Conference, April 2004, Palm Springs, CA

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[11] Mukhopadhyay V, Sobieszczanski-Sobieski J, Kosaka I, Quinn G, Charpentier C. Analysis, Design and optimization of Non-cylindrical Fuselage for BlendedWing-Body (BWB) Vehicle. AIAA 2002-5664. 9th AIAA/ISSMO Symposium on Multidisciplinary Analysis and Optimization, September 4-6, 2002, Atlanta, GA. [12] Mukhopadhyay V, Sobieszczanski-Sobieski J, Kosaka I, Quinn G, Charpentier C. Analysis, Design and optimization of Non-cylindrical Fuselage for BlendedWing-Body (BWB) Vehicle. Journal of Aircraft Vol. 41, No. 4, July-August 2004. [13] Mukhopadhyay V. Blended-Wing-Body (BWB) Fuselage Structural Design for Weight Reduction. AIAA 2005-2349. 46th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, 18-21 April 2005, Austin, TX. [14] Pearce P. Structure in Nature is a Strategy for Design. MIT Press, Cambridge, Massachusetts, London, 1990. [15] Smith Y, editor. Wing design Would Be More Fuel Efficient and Environmentally Friendly. http://www.nasa.gov/vision/earth/improvingflight/blended_wing.html [16] Tenney D, Pipes R.B. Advanced Composites Development for Aerospace Applications. http://techreports.larc.nasa.gov/ltrs/PDF/2001/mtg/NASA-20017sampe-drt.pdf [17] Tooren MJL van. Sandwich fuselage design. PhD. thesis report. Structures and materials laboratory, Faculty of Aerospace Engineering, Delft University of Technology. Delft, December, 1998.

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Delft Science in Design 2 M. Eekhout et al. (Eds.) IOS Press, 2008 © 2008 IOS Press and the authors. All rights reserved.

Application of new technology as a starting point in Industrial Design. Challenging Graduation Projects Jan Jacobs

Professor in Industrial Design/ Delft University of Technology, Faculty of Industrial Design Engineering, Delft, the Netherlands. Abstract This paper gives a compact view on two graduation projects from the Faculty of Industrial Design Engineering. These projects have the challenging application of new technologies as a starting point. Among researchers in the faculty is a strong belief that human needs and possibilities are leading as a starting point for the development of really new products. Everyday reality shows however that technical innovations still are the main driving forces for new products or systems. Fuel cells or hybrid power trains are examples of technology, stimulating our students to develop highly interesting prototypes. The results of these projects act as serious stimulators for further development. Keywords: DSiD2, industrial design, graduation projects, application of technology, fuel cells

1. Introduction Industrial Design started in the 19-th century as the integration of technical possibilities and human aspects, such as: pleasing, beautiful and usable. The main starting points for new products sometimes are new technical solutions, and sometimes are aspects as style or fashion. Due to this situation there is an, ever present, interesting tension. Until today this tension plays an important role in industrial design. Sometimes trends and fashion dominate, but not necessary leading to really new products. Sometimes aspects as safety dominate, for example in the development of cars. And very often new technologies lead towards new products. Nowadays products that are based on further developments in technology surround us. Among them are: computers, CD-players, mobile phones, digital cameras. Because the Faculty of Industrial Design not only deals with technical implications but also with humanities, there is a strong believe among a group of young scientists that research in the field of human needs and possibilities should especially act as the starting point for new developments. Technical solutions should be based on these demands, or: these

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demands should not be influenced by the application of technology that was in a way ad-random developed. However: the everyday reality shows that there are thousands of technical research patents, waiting for application. There are new technologies that are knocking on our doors for over decades. One of these developments is the fuel cell. The fuel cell became world famous when Mercedes Benz intended to use it in its baby Benz. The whole structure of there A class, with a double bottom, was based on the use of that system. When they had to decide to use a traditional combustion engine, instead of a fuel cell, they forgot to compensate for the total balance of the vehicle, leading to severe problems in the so-called Elk test. Some years ago the Faculty of Industrial Design Engineering started the Delft Design Institute (DDI), where researchers and students work together on challenging projects and products, sometimes acting as as showcases to the world. Within the DDI there are three research themes: • Energy and Intelligent Products • Mobility • Medisign. Between the fields Energy and Mobility there were recently several students who were triggered by the possibilities of fuel cells or hybrid systems. This paper tells the story of two of these graduation projects: the development of a fuel cell powered outboard motor and the design of a fuel cell powered scooter.

2. Graduation Projects in Industrial Design Engineering. As in other Delft disciplines the graduation project is the climax in the educational structure. As a tradition some 85% of these projects take place within industry. There are of course also strong relations to private scientific organizations. The last decade we have seen a shift in the content of graduation projects from solutions for real products, such as: a new coffee maker or a new vacuum cleaner towards the development of interesting concepts: from solving the problem of boarding in Schiphol to new concepts for fire fighting trucks. So: new graduation projects are less focusing on everyday problem solving. They are more related to exploring new solutions and opportunities. These days’ students in graduation projects can follow two possible directions in their design process. There is a more traditional ap36

proach, based on a structure that takes steps as: orientation, analysis, ideas, concepts and prototype. And there is a structure that focuses on the design of the wanted interaction between user and product, before it comes to develop ideas or concepts, the Vision in Product design ( ViP) method. Because there was a wish for real functioning prototypes, and not just concepts, the students in the two projects used the more traditional method, with a strong focus on the realization of working models. Within the existing research portfolio of the faculty one of the themes is a focus on sustainable energy systems. The two projects that will be described are positioned within this field. As usual the students have searched for cooperation with industry. In the case of the outboard motor there was a thorough cooperation with the design agency Springtime and Yamaha Europe. In the case of the scooter we tried to get cooperation with Piaggio, the manufacturer of the Vespa scooter in Italy. As that turned out to be impossible, again Yamaha was involved, but only on a low level.

3. The design of a fuel cell powered outboard motor. Danish student Thomas Jensen, became, after his bachelor in engineering, interested in Industrial Design and due to the international reputation he choose Delft University and the master program Integrated Product Design ( IPD). When it came to investigate possibilities for his graduation project one of our PhD students, Hanna Hellman, came up with the idea to merge fuel cell technology and the marine environment, with an outboard motor as an example. It could be an opening in this rather traditional field and this project could, as an example of the application of this technology, be used as part of her PhD research. 3.1. Background. Besides outboard motors with an internal combustion engine, there are, for surroundings where noise or pollution is less wanted, electric outboard propulsion systems. Under circumstances where a more powerful electric motor would be suitable there are many constraints due to volume, weight and charging. Fuel cell technology gives the opportunity to use hydrogen to produce electrical power. Storing energy in hydrogen, compared to storing energy in batteries, gives the possibility to make the whole system smaller and lighter. The basic principle of fuel technology is known for many years. Although this technology has already been used successful in some application fields, it is still too expensive and not reliable enough for mass production.

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However, numerous prototypes were developed, challenging further development. 3.2. Focus. After a thorough orientation and analysis phase the following decisions were made: • The outboard motor should, on the basis of market research, be developed for a lower power range, • The fuel cell system will be based on the Proton Exchange Membrane (PEM) architecture, • The hydrogen will be stored in pressure vessels at ambient temperature. 3.3. Target groups. Target groups were selected on basis of the possibilities that resulted from the analysis, among these were: • Sailors, with a focus on boats shorter than 8 meter. These boats use an outboard motor, due to the fact that the price of installing an inboard motor is too high, compared to the total price of the boat. • Fishermen, implementing a fuel cell system in a fishers boat suits better the conditions for environmental friendly behaviour. 3.4. The Pod. During the idea-phase of the project series of interesting proposals were developed. But, by further discussing the target groups and their needs a whole new idea emerged. This idea was called “ the Pod”. The Pod could be: “a self-contained floating unit”, which means that all components are included in one device. Once this concept was chosen, further research and development was necessary. 3.5. Designing The Pod. The first question that came up was: in what circumstances will this product idea be used? In what way does this idea influence the products it is connected to? Could this idea also be used as an independent product? A list was made of primary and secondary use. Primary use focuses on the use with smaller boats, as for fishing, and the use as an outboard propulsion system for sailing boats. The secondary use deals with towing and pushing of boats under different circumstances; and the use in water sports, as a kind of water scooter, or for knee boarding.

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The Pod could eventually also be used as a rescue device. The concept phase of the design process started as a balance between working from the inside out and the other way around. Working from the inside out, there was a thorough survey on useful components and their possible further development. Chosen components were configured to several proposals, following the scientific approach of Muller, described in his book.

Fig. 1. Structural layout of components

At the same time a lot of time and energy was spend in designing a suitable form for this completely new product. Not only the wanted aesthetic form was determinative for the result, but also new possibilities of use influenced the final form and details.

Fig. 2.Final proposal of the Pod.

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To investigate the different possible shapes several foam models on a scale of 1/3 were made. Discussions with professor Keuning from the Department of Maritime Technology lead to a product that also suits all formal marine requirements. The result of this graduation project is a very interesting and certainly new product that challenges our imagination and that will act as a stimulator for further research and development.

4. The design of a fuel cell powered scooter. 4.1. Introduction. Since traffic in towns becomes more and more problematic and public transport is overcrowded, people are looking for alternatives. Sometimes those situations lead to the rediscovering of almost extinct products as scooters. Presented in 1946, the Vespa ( wasp in Italian) was a real innovation in transport in the crowded areas of Italy. The concept was a huge success, a success that remained through the fifties and sixties of the last century. In spite of the fact that the role of the scooter in traffic seemed to be dominated by cars and motorcycles, the scooter had a very surprising come back in the nineties. Since then there are two striking target groups for scooters. Youngsters in the age of 16 to 18 years old and elderly people who will or cannot afford a car. Recently these market domains are expanded with the use of the scooter by young professionals, due to the ever-increasing traffic situation in towns. So: the design of a scooter is also an interesting subject to act as a demonstration project in the field of the use of fuel cells, batteries and electric drive train technology. 4.2. The project context. Making a change to existing systems requires large investments. During the first phase of such a transition it can be of high interest that projects with tangible results are started to demonstrate possibilities. Such projects may help to evoke interest from industry, policy makers and consumers. The goal of this project was defined as: design a fuel cell powered transportation device, suitable to transport at least one person. As a result of market research, it should be a hybrid propulsion system, consisting of a fuel cell system, energy storage and an electric motor to drive the product.

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Key aspects of the project were: • exploring the solution and design space for such a product • investigating different shapes and designs • investigating different product architectures • creating possibilities to use the propulsion system as energy source for other purposes. The research lead to following conclusions: • the fuel cell PEM system (as also proposed in the outboard motor) should be used, although fuel storage would be complex, • Li-ion batteries should be used for storage, at this moment they are best choice to be used in electrical drive trains, • The use of a hub / wheel engine is the most promising way for traction. • From an analysis of prospective users a scenario of use was made. “Urban commuting” seemed the most realistic scenario and target groups were defined. 4.3. Technical design process. First the driving system should be developed. The required performance depended on a Taiwanese study on driving cycles in an urban environment, which resulted in the following: • an average speed of 30 km/h should be possible • the range before refueling should be 200 km. • the acceleration should be at the same level as regular scooters ( > 3,6 m/s2 ) • a maximum weight of the product in total of 130 kg. In addition there were requirements for special situations: • a top speed of 45 km/h • a speed of 10 km/h on a slope of 15 degrees. These starting points defined the required performance. In the end a 700 W fuel cell system was chosen, combined with highpower and high-density batteries, such as Li-ion. The hydrogen to be used could best be stored in a 700 bar compressed system. 4.4. The synthesis. To get inspiration Crijn Bouman, our graduation student in this project, purchased a used Peugeot scooter. Based on analyzing and dismantling this scooter he came up with several structural variants, using Mullers

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method. In this scientific method the main components of a product are arranged in different positions to generate ideas for the basic structure. The result of this exercise was a structure where most of the components are positioned in the front of the scooter. Also front wheel drive was chosen. Both Crijn as the mentor team were very curious whether this solution would lead to better handling. The size and proportions of the chosen structure were explored by making full-size foam models. After all the whole exercise lead to three concepts: • a concept called: “Arrow Head”, with a strong focus on a form that supports the front wheel drive, • a concept called; “Briefcase”, designed as small as possible, with components that are connected by a frame, • a concept called: “Platform Transporter”, the components are mainly horizontally oriented. The third concept was chosen, a product idea with a clear link to existing scooters, but with numerous new solutions. 4.5. Materialization, detail design. Because there was an emphatic wish to develop a full demonstration prototype, all choices in this part of the design process were made with the intention to create an attractive prototype with a high appeal factor. The decision to make a working prototype turned out to be a real challenge. Although some components of the Peugeot scooter were used, most of the parts for the new scooter had to be developed separately or had to be adapted to the new situation. After month of work, with the cooperation of the workshop of Industrial Design and many, many others, the prototype was finished just before the graduation date. Test drives showed that the product had the high appeal factor that was wanted. Since the result could be seen on the Internet, the number of hits in Google have shown us how many interest there is, worldwide, in this kind of revealing products. Crijn Bouman is now working in his own company, focusing on electric power solutions.

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Fig. 3. Working protoype of the scooter.

5. Conclusion. Still, the results of the application of technical research and development are very important stimulators in creating new products. Many students are triggered by these developments when they also have a direct relation to solve upcoming problems. Nobody should be amazed that fuel cell technology, which already for more than decades is on the threshold to implementation, is one of the items that appeal to their imagination. In designing examples of applications in their graduation projects, the two students certainly have brought this kind of technology a step further to realization. In the mean time new students have taken the baton to demonstrate the application of new technology. One of these students also has developed a working prototype of a scooter, but now with focus on using LPG in a hybrid structure.

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References [1] Thomas Gregers Jensen, “A fuel Cell Powered Outboard Motor”, Graduation project, Feb. 2006, Delft University of Technology, Faculty of Industrial Design Engineering [2] Crijn Bouman, “ Design of a fuel cell powered scooter”, Graduation project, July 2006, Delft University of Technology, Faculty of Industrial Design Engineering, Delft Design Institute. [3] Willem Muller, Order and Meaning in Design. Lemma, 2001.

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Delft Science in Design 2 M. Eekhout et al. (Eds.) IOS Press, 2008 © 2008 IOS Press and the authors. All rights reserved.

Blob-Shells: Composite Stressed Skin Roofs for Liquid Design Architecture Mick Eekhout1, Ronald Visser2 1

Professor of Product Development, Delft University of Technology, Faculty of Architecture / Director of Octatube Space Structures, Delft, The Netherlands, [email protected] / [email protected] 2 Researcher, Chair of Product Development, Delft University of Technology, Faculty of Architecture, Delft, The Netherlands, [email protected] Abstract This article describes the design, development & research build process of a new generation of shell roof structures for architecture. The result marks a new era, the renaissance of the shell structures, once popular in architecture in the 1960’s, but disappeared since. Liquid Design Architecture enhances a more free and complex geometry of buildings. The main attention in this contribution is given to the ‘free form’ roofs of the Rabin Center in Tel Aviv (architect Moshe Safdie). The principle idea was initated in discussions with colleagues from aeronautic and yacht design. The subsequent process of design & engineering, made use of state-of-the-art design and engineering computer programmes, but relied even more on the ‘out of the box’ abilities and imagination of the technical designers. The production stage was greatly assisted by the transfer of technology from yachting industry, although the architectural application, mainly in its size, but also in transport, shipment and assembly had to be developed further on the building industry’s level of technology and pricing. The development owes much to the interdisciplinary design vocabulary from the different designing faculties at the Delft University of Technology. Professors Adriaan Beukers and Michiel van Tooren became involved and gave a second opinion to the client on the developed sandwich composite technology. After four years of hard labour, great risks on many frontiers and engineering and production experimentation a new generation of shell structures is born, giving possibilities for other wild architectural ideas like the Mediateque in Pau, France, according to the design of architect Zaha Hadid of London. Keywords: Collaborative Engineering, Blob Technology, One-off Industrialization, 3D Composite Components, Design & Build Approach, Product Development, Sandwich Constructions, Technological Innovation, Blob-shells, Free Form Design, Fluent Architecture.

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1. Introduction Technical design of roof and façade structures for architecture has accelerated in the last 3 decades from well-known traditional solutions into technically innovative solutions. After the development of stretched membrane structures in the 1970’s, systemized metal space structures in the 1980’s-, sophisticated tensegrity structures in the 1990’s, glass envelope constructions and load bearing glass structures of the last decade it is now ‘Liquid Design’, ‘Free Form’ or ‘Blob’ architecture that caught the interest of young architects. The description of this type of architecture originates from a free form geometry, non describable with any regular mathematical formula. In a sense it is a direct consequence of technology driven interest of architects. Having learned the newest generations of 3D design and engineering computer programs, they are now capable to design (geometrically) complicated virtual 3D buildings that seem completely real on the screen without even being build. Yet the route to realisation is paved with numerous technical (and some social collaboration) experiments to produce the technical 3D components of these ‘Blob’ buildings. Often these components will be 3D-curved. Usually they are one-offs in their shape and non-repetitive. The extreme contradiction is the request for custom-made components versus the low budgets of the building industry on the one hand and researching and developing technological innovations in the speed of a real time building project process in order to acquire the new technology just-in-time on the other hand. The aid of other design professions like aeronautics, ship design and industrial design is very inspiring and necessary in order to develop a new ‘Blob’ technology with the 3D forms, yet fitting within the modest average m2 budgets of the building industry. Extension of the building industry’s traditional integration is necessary in order to develop suitable CAD/CAE, CAM/CAB procedures and special production and surveying technologies. In this case producing one-off GRP stressed skin sandwich components made it possible to make larger spans for the roofs , though in an arbitrary form in order to become true 3D-roofs. Designing structural systems for use in architecture – including the necessary research & development, but always leading to actual realizations – is the core of the author’s personal attitude towards designing. Many of the structural and constructional designs made as an architect, as a pioneer of space structures and as a structural designer, have followed an incremental approach of step-by-step with ever increasing know-how and elevated insight. This started for smaller projects in the Netherlands and led to applications of increasing scale both in the Netherlands and abroad. This approach is adapted to the (smaller) scale of projects in the building industry, their ever deviating character depending of the designing architects, their real time planning schedules and the desired degree of experimentation of the technical designer. The projects are performed as

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‘design and build’ contracts in the Octatube company at Delft and sometimes in the architect’s office. The position as the professor of product development at the TU Delft and the range of collaborating faculties within the Delft University of Technology itself offer excellent opportunities for contemplation and sharpen the mind amidst of scientific design colleagues from different disciplines. This particular second congress of Delft Science in Design enables us to continue the debate on the merits of Scientific Design at TU Delft. To discuss the merits of design, development and research and to discuss the valorisation side of designing, developing and researching as the major activities of the TU Delft. Design is able to tunnel results of scientific research to society. The relationship between research and design are mutually indispensable. Some of the building systems, which were developed in the author’s offices through time (see scientific site: www.mickeekhout.nl) have been boosted and accelerated by know-how from other professions, faculties and industries. Close traditional relationships are kept between architecture and (civil or) structural engineering.

2. Inventions, Innovations and a Competitive Market Amongst the ever-recurrent obstacles in component design and product development in architectural projects are the low thresholds in the building industry, the lack of interest in entrepreneurial experimentations and the overall tendency for copying the results of the experimentation of others, minimizing the experimental expenditure by the lazy policy of ‘wait-and-see’ or the ‘me-too’ effect. This is counter-positioned by the experimenting designer, dragging an office and a company behind him that follows his whims, willing and able to undertake all technical adventures in the process. This has been a life-long attitude. After the initial product design and developments of a new generation of structures has resulted in successful applications, professional publications are written. After publication new clients become interested but the competition has been awakened, too this flow of happenings haunts every new invention. It was this framework that made the Europeans invent the protection system of patents in the 19th century. But with many different systems at hand and even more differentiated applications, patents do not shield inventive development work in architecture. The number of repetitions is low and the variety asked in different projects is high. The eternal fate of the architectural and structural designer is to look for new horizons: either new markets for existing products or new products for existing markets. Luckily a number of ‘me-too’ competitors for example in Israel made a mess of their copied systems, but alas these projects were lost in the tender stage any way. For the Hashalom (Peace) project in Tel Aviv the client regretted his decision to subcontract an Italian glass com-

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pany for frameless glazing, changed his mind, withdrew the contract from that consortium and contracted the original designer company, who redesigned, engineered, produced and installed the project in a miraculously short time. Because the building calendar has its own speed. In the last years prices of frameless glazing systems are dropping due to competent and incompetent rivalry. Although experimentation with a large distance between production and building site adds to the possibility of a negative outcome, the composite wings of Tel Aviv are an example of a well-defined experimental component design & development for one specific project. After successful completion this could lead to an entirely world-novel technique of engineering and producing roofs for liquid design buildings. In its turn, this hopefully leads to the establishment of a new Dutch consortium of small and medium-sized enterprises (SME). It is further to be expected that after duplication, multiplication and systematization of the developed technology the laws of economics interfere and that the enterprising structural engineer has to develop ever new products and systems.

3. Stage of Tender Documents In November 2002 the client “Friends of Yitzhak Rabin’ issued tender drawings and specifications of a design by architect Moshe Safdie from Boston USA as a part of the Yitzhak Rabin Center in Tel Aviv. The design of the building was an elaboration and extension of a former auxiliary electricity plant near a university campus of Tel Aviv in order to become a memorial building for the late prime minister Yitzhak Rabin who was murdered in November 1995. He was seen as a peace maker and was rewarded the Nobel price for Peace in 1994. His activities led to the socalled ‘Oslo peace talks’. The entire building was tendered out in different lots. This particular tender provided for two building parts: the ‘Great Hall’ and the ‘Library’. These two big rooms both have large glass façades facing south towards the Ayalon valley below. Both hall designs have remarkable and plastically designed roofs to resemble dove wings as a tribute to peace maker Rabin. Moshe Safdie is well known since he designed the dwelling complex ‘Habitat’ of Montreal as a part of the World Exhibition of 1967 when he was a 27 year old architect [Kohn, W. et al, 1996]. This was the author’s second collaboration with architect Moshe Safdie: the first one being the conical glass wedding hall of the Samson Centre in Jerusalem, overlooking the valley adjacent to the old city of Jeruzalem near the Jaffa Gate. Safdie is an almost prophetic designer who designs beautiful spaces with dramatic interiors. In the last decades he redesigned the Jewish quarter in Jeruzalem. The Samson glass dome, overlooking the ancient city with its golden colour in the afternoon, is used for marriage feasts and other celebrations and is a great success. The hall is used for

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weddings twice a day. Safdie was very satisfied with the alternative design proposals for the cone and with the realized technical accuracy. For the new project the complicated liquid design roofs of the Rabin Center contained in the tender were analyzed by ARUP New York. They proposed a welded grid of steel beams in a rather arbitrary running of the open steel profiles with a layer of concrete on top. The specification left the roof cladding up to the contractors. On top of this the architect requested a seamless solution over the entire roof. Not a very appealing specification for a design & build company which had to transport all items over a distance of 5.000km. For two months the tender drawings and the thick specification were not given much notice. The ‘seamless’ requirement would make any prefabricated system very difficult and the success would depend entirely on local labour and supervision, which a producer of industrial and prefabricated systems does not like. However, the client and his building manager kept on reminding of the tender date and even postponed the tender.

Fig. 1-2. Tender drawings made by ARUP. Left, ‘The Library’ and right, the Great Hall.

Fig. 3. Architectural model of the Rabin Center, Tel Aviv (courtesy: Moshe Safdie & Associates).

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Fig. 4. Plan of the Rabin Center, Tel Aviv (courtesy: Moshe Safdie & Associates).

4. Development of Cladding Systems Through Projects When struggling with an alternative technical design for the new cladding of the Atomium of Brussels (dating from 1958), TU Delft’s professors Adriaan Beukers and Michel van Tooren (Faculty of Aeronautical Engineering) stated in their inaugural speeches that “aeroplanes always leak and condensate” [Beukers, 2003; van Tooren, 2003]. This one sentence inspired the quest for a recladding concept of the 9 spheres of the Atomium. The end result was that in the technical proposal each of the 18m diameter domes was to be clad with 2 x 8 spherical segments in the form of half an orange peal, size 14m long, 8 m wide and 3m curved. This resulted in a solution in which the total length of the seams was restricted to only 20% of the original joint length, which was 20.000m’. Even a low leakage percentage of 1% would result in 100m’ of leaking upper seams. In the developed proposal the joints were detailed much like the oldfashioned ‘Double Improved Dutch Roof Tiles’ with double internal joints that never had to be replaced or maintained. Leakage problems would belong to the past with this solution. A patent was applied for. So in this case, an unexpected impulse from aeronautics helped to develop a new concept. Alas the politics around the tender were quite non-transparent and the contract for execution was awarded to a Belgian party. The design proposal keeps its value, however and is published here for its inspiration, returning to the alma mater of the original inspiration.

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One year before the tender date of the Rabin Center, the design , engineering and building of the Municipal Floriade pavilion (now named Hydra Pier) of Asymptote Architects from New York was completed. One of the three experiments in that project were 3D-aluminum panels of 5mm thickness which were deformed through explosion on negative concrete moulds (based on machined positive polystyrene moulds). This production process originally seems to have been used in Russian submarines in the 1960’s. The paths of technology transfer are sometimes strange. This process took place at the premises of the Exploform company in Delft. This complete production procedure from engineering drawings, via Styrofoam negative moulds and reinforced concrete moulds, the explosion process, the measuring and fitting on timber moulds up to the finished and installed watertight and coated panels proved to be a feasible, but also a laborious process to fabricate as 3D-curved panels. It was the first time in the world that 3d aluminium panels for architecture were produced along these complicated paths. Although the cladding was successfully realized in this Floriade project, the m² price of the 3D panels was too high for a next project in the building industry (which in the Netherlands was also at the edge of recession at that time).

Fig. 5. Close-up of the Atomium, Brussels.

Fig. 6. Schematic drawing of the proposed division: 2 x 8 spherical segments in GRP.

A cheaper system had to be developed for the next project. Haiko Dragstra, a very inventive mechanical/electrical engineer co-operated in this project from his company Complot, Delft and came up with the idea to take thinner sheets of aluminium, laminate a foam panel with parallel transverse sleeves and an epoxy laminate as the inside skin in order to make a strong and stiff panel. So these panels were half aluminium, half composite sandwiches.

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One step further was to make the complete panel out of two composite skins with a foam core and have the outside skin coated, if needed in an aluminium metallic colour. One does not see the difference from painted aluminium or steel panels and polycarbonate components in cars. However, at the time Asymptote Architects did not like the idea of mixing different materials, according to the contractor. It was this line of thinking that brought the development further. Haiko Dragstra was able to machine foam blocks into any desired form by the machines he built himself. Machining according to CAD data is possible both for the top and bottom layer of the foam. The total surface of the roof was subdivided in blocks and glued with the machined blocks of foam. Subsequently structural layers of glass-fibre reinforced polyester were applied to each side. These experiences came on the table when brainstorming on the new principles for the 3D wings of Tel Aviv.

Fig. 7. Video captions of an ‘Exploform explosion’ in a water basin (from: exploform.nl)

Fig. 8-10. Left over polystyrene moulds used to make negative concrete moulds (left), exploformed aluminium panel (center) and fitting of a panel on a wooden fitting mould (right).

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Fig. 11. 3D curved roof of the Hydra Pier, designed by Asymptote Architects

5. Giant Stressed Skin Sandwich Constructions So in a few brainstorms between designers and co-makers of different background , collaborating in a tender consortium, this was the basic idea: make the roofs as giant surfboards of foam with stressed GRP skins on both sides. The size of the roofs, subdivided into 5 different roof wings was maximum 30mx20m. The company Polyproducts of Werken-dam and her engineering office was invited to join the tender team of Octatube, as well as Haiko Dragstra. In a month time three successive brainstorms were organized on the product idea, the structural concept and the logistics & pricing. It was decided to work out and price the revolutionary stressed sandwich skin alternative as well as the original tender specification of the steel structure with a non-described, free covering as the variation. The steel deadweight of the steel structure was estimated by ARUP, so a price of the original design with the steel structure, supposed in curved CHS (circular tubes) with cladding variations in different foam layers, levelling and top layers was feasible from existing data and a little imagination. The cladding proposed for the original tender design was derived from the mega-sandwich idea, but now in a thinner scale version of 50 to 80 mm sandwich thickness, as it only needed to span the space between the steel structure elements (max. 3m). The budget calculations came out on a level of 2.5 million Euro for the original design with a thin 80 mm thick GRP sandwich cladding instead of concrete. The alternative design with the full load bearing stressed skin sandwich would add up to more than 4 million Euro, largely due to the high estimates of the production of the polyester parts. The producer had

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never done a project of this magnitude but knew how to operate the production of sandwich panels using vacuum injection methods. It was argued in the final brainstorm that the maximum extra costs would not be acceptable to exceed the sum of one million Euro extra, resulting in a total alternative price of 3.5 million Euro. It was foreseen that any architect would fall in love with the alternative idea of the self-supporting stressed skin sandwich. This was the solution faxed to Israel, just in time before the tender closing date, accompanied by a letter explaining the two quoted systems: the original specification (with a variation on the tubular structure and the cladding) and the alternative for the composite sandwich panels.

6. Amazing Solution! Only two days after the tender closed a telephone call was received from the local representative architect Zachi Halberstadt, speaking on behalf of Moshe Safdie. He gave the compliment that the architect saw the alternative proposal as “an amazing solution”. Halberstadt invited for an immediate meeting in Tel Aviv the next day, so that the idea could be presented to the entire building commission. At this presentation the polystyrene models that Haiko Dragstra had machined in a demountable model scale 1 to 40 were shown. The models also proved that the corner details in the design had not yet been accurately designed and that the overall stability was not satisfactory. The design needed a considerable attention in the design perfection. But the enlarged scale model showed the seriousness of the tenderer. The building commission was astonished after hearing the explanation of the construction and the consequential logistics of the alternative proposal. The five big wings would have to be constructed in one of the empty ship building halls in the Netherlands, like at Krimpen aan den Ijssel. This size of hall was necessary as the wings would have to be turned upside down after application of the stressed skin layer on top in order to apply the lower layer. The milling polystyrene machine had to be moved nearby this production hall and to be installed adjacent to the assembly area. After gluing the polystyrene blocks, the top skin could be applied. That is, if the polystyrene blocks would form a roof wing in horizontal position. After completion of the GRP top skin, the object had to be turned over and the bottom skin had to be applied. After the completion of the surfaces of the shells, they would be loaded on an open inland vessel and towed to the port of Rotterdam, where the cargo would be loaded on a specially chartered ship in which the 5 finished shells could be stacked vertically. This ship would sail to Tel Aviv and anchor at sea in front of the city. From this location a giant freight helicopter would lift the roof wings individually from the vessel on a route to the shore, 5km

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inland during the night, to position the roof wings on the flat open building site. A mobile crane would then swing the roofs on top of the columns. The whole shipment and air transport was pretty special and expensive. After explanation of the logistics of this alternative proposal, the representative Boaz Brown heard the architect Moshe Safdie mention to the chairman of the building team in Hebrew: “you should try to get the one million extra” or words of that meaning.

Fig. 12. Schematic drawing of a shipyard building with roof-wing positions

Fig. 13. A ‘wing’ transported by helicopter (photomontage).

7. Extremely Innovative, but Expensive The client’s building commission went into a separate meeting. After one hour of fierce discussions, the outcome was that the tender original with the thin GRP covering was practically on the average tender price level. On the other hand they noted that the alternative proposal with the composite sandwich constructions was indeed very attractive from viewpoint of its extremely innovative design and construction, but was priced one million Euro over budget. By the way, from a selling point of view and knowing the intellectual value of the alternative proposal, it would have been stupid to sell it at a lower price than the tender proposals. Usually technical alternatives are more efficient solutions for the contractors and tend to be lower in price than the original. A more expensive alternative is rare and hence extraordinary. Starting with the highest price and the best technology, may end with a contract at a compromised price. An ‘avantgarde’ designer also looses projects to competitors as they can copy the new technology after one completed project and execute this without the

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necessary research and without the higher Dutch labour costs of Octatube. But in the case of the wings, there was not a suitable technology yet in the world. The alternative idea was to become a technical world novelty and Moshe Safdie understood this.

Fig. 14-15. Sydney Opera House, architect: Jørn Utzon

The discussion at hand with Safdie was about the Sydney Opera House (built in the 1970’s) and how lucky architect Jørn Utzon would have been if he could have used stiff GRP sandwich panels instead of the heavy concrete shells and ceramic tiles. Even though the realization of the Opera House meant a major step in the history of structural engineering. The Sydney Opera House, with its problematic realization, its time elongation, budget explosions, growth of Ove Arup Engineering and the architect’s dismissal from the site, is now the most admired building of the continent of Australia. Through these discussions it was noticed that the marketing concept apparently had worked. Safdie appraised his belief in stating that he thought that the idea was amazing and never done before to his knowledge. If someone could make it work in his opinion, it was to be Mick Eekhout cum suis. The response of the chairman of the building committee was to come up with different logistics for the GRP sandwich proposal in a manner that the price level could be lowered to 2,5 million Euro. He suggested that it might be possible to transfer the foam machining and the GRP production to Israel in order to reduce costs for shipment and labour at the same time. This was the message taken home on 29 April 2003.

8. Rethinking the Alternative Back in Delft the consequences were discussed with the in-house engineers and the external consortium tender team members. The plan was born in the airplane from Israel to the Netherlands. If the GRP sandwich roofs could be realized, it would be a hit on the world market. It should be possible to transfer more labour to Israel in order to reduce costs and

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talk to new Israeli partners if the current partners would let the project down in order to realize this proposal. The first idea was to try to decompose the big wings into transportable components, which could be assembled on-site on a jig, smoothen the visual surfaces between the individual segments, to finish the outer GRP layers and give the shells a final top-layer or top-coat. Complot could machine the polystyrene blocks locally and Polyproducts could set up an Israeli GRP plant in Tel Aviv on the building site. The most likely position to assemble a wing would be in a vertical position. This way both outer skins on the polystyrene core foam could be treated simultaneously and the shrinking of the foam could be controlled. Subsequently, the roof wing could be easily lifted by a mobile crane from between two 20m high scaffolds. However, after a few more meetings it appeared that machining the polystyrene blocks in Israel seemed very expensive. The subcontractor was not experienced in estimating larger productions than mock-ups. He had never exported his products and felt not comfortable in unknown areas. The bottom price of co-maker Polyproducts in Israel did not give much hope either. So the co-maker would think the world of the high number of innovations in this project and kept his price high. At the same time the usual squeezing of tender prices was set in, which forced the sales department to land on another price level altogether. For sake of financial negotiations, another point of view had to be taken in. It was decided to put all first emphasis on the original design with the internal steel structure and sandwich coverings. To take an internal and hidden steel space frame with a locally made sandwich panel system on top and bottom, forgetting for a moment the attraction of the possible world novelty of the stressed skin sandwich constructions, just to stay in the race. Based on this price and on the technical abilities Moshe Safdie was still convinced that Octatube could do the best job. Therefore Safdie pressed the client to take a wise decision: to issue an (experimental) pre-engineering contract to execute the design development and make material prototypes. A separate pre-engineering contract (or prototype development contract) was drafted for redesigning some steps on refinement of the roof models, and investigation in prototypes for different composition, to convince the makers themselves of the attainable quality and subsequently the architect and the client. After this decision the process went into redesign development and developing prototypes of segments of the construction of the Great Hall with the most complex wings, assuming that the details of the Library would follow those of the Great Hall.

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9. Redesigning, Pre-Engineering and Prototyping In the course of the design development of this first prototype development contract the redesign had to follow the rough contours given in the tender stage by the Safdie office. The official data of the three wings of the Great Hall were handed over by the architect’s office as a Rhino scan from a material 3D model. The data within this model needed serious converting, since they proved to be inadequate and inaccurate for further engineering. Through analysis of different cross sections of the model and connecting these in fluent lines, a new and usable 3D model was developed. This ensemble was redesigned in another modelling program: Maya (3D CAD software). This software turned out to be an excellent medium for designing the different components. Also, the same software enabled constituent parts to be defined and combined into the total composition of the project: five sandwich roof wings, the steel columns, the three skylights and glass panels in the 4 glass facades. It became unavoidable in this stage that the final contract had to include also the reinforced concrete walls as well as the support plates of the concrete tops for anchoring of the columns, as the particular geometry of the roof wings would determine the concrete work below, although this concrete work was part of the main contractor’s lot.

Fig. 16-17. The Rhino model of Moshe Safdie & Associates and the first redesign in Maya by Octatube.

Fig. 18-19. Two construction types: a steel structure of CHS circular sections (left) and the structural sandwich structure (right).

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At the same time a global structural analysis was made of the structural behaviour of the GRP wings and the steelwork. During this time the two quoted construction types were both worked on: the original version of a tubular steel structure of systemised CHS circular sections, covered with a thin GRP sandwich as the roof covering and the alternative designer’s option of the structural sandwich composite structure. Sales negotiations with the client had resulted in an unavoidable change on the purchase side of the co-maker for the polyester work. The price of Polyproducts was remained stiff on a too high level and they were terminated as a co-maker in the process. Holland Composites Industrials (based in Lelystad, NL) was invited as the polyester co-maker in their place. They had previously made hulls of motor yachts and sailing yachts in glass fibre reinforced polyester (GRP) up to 30m length with the vacuum injection method. This was an excellent starting point for the development of the structural sandwich panels. They employed the firm Solico Engineering (based in Oosterhout, NL) who started to globally analyse the GRP roofs. The two structural analysis of Octatube and Solico were compared and matched.

Fig. 20. Structural analysis of deformation of the GRP sandwich roofs made by Solico. Left, the upper and lower wing of ‘The Library’. Right, the upper wing, the central body (made of steel with a GRP covering) and the lower wing of ‘The Great Hall’.

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At the same time, prototypes were made of both construction types: the tubular steel structure with a light composite sandwich polyester covering and the alternative designer’s solution of the integral composite sandwich. Both prototypes were shown to architect Moshe Safdie, together with the first results of the Maya computer redesign work in July 2003. In the mean time this pre-engineering work had indeed resulted in a dramatic reduction of the cost price as the engineering team became more and more familiar with the experimental aspects and how to resolve these. The original quotation was reduced to around the original average price level, thanks to the results of this pre-engineering contract. So the preengineering contract, as it was seen by all involved in the process including the client, was a wise decision. Such pre-engineering prototype contracts are often proposed for experimental projects in the Netherlands, but hardly ever rewarded. The effect is that both sides are getting accustomed to the characteristics of the experiments at had and that the makers loose uncertainty, which would result in adding high contingencies in the global price. Clients mostly refuse these pre-engineering contracts out of fear for monopolisation of the involved contractor. In that case the client could also have the architect undertake such a prototype development contract with restricted legal conditions. And indeed, monopolies are almost a natural consequence of specialization.

Fig. 21. First prototype with a stressed membrane.

Fig. 22. Third prototype to be locally produced.

Fig. 23. Fourth prototype, a prefab sandwich construction.

10. Results of the Prototype Development The course from redesign, pre-engineering and prototype development to final design took one year involving 5 to 6 engineers. The architect visited the development laboratory in Delft twice in that time to check the progress on the design and the new prototypes that were made on his specific instructions. It was agreed that, in contrast with previous projects involving Blob structures at the engineering department, there would only be one party involved with computer work. In this case the engineering department would be in the lead and the architect would only supervise and give instructions behind the monitor. It would also put the legal re-

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sponsibility on the same table as the technical development responsibility. The impulses from the development of the prototypes, the production methods involving moulds and injection production plus the future assembly of the structural seams and the structural behaviour of the total wings, all had a deep impact on the final design and had to be fixed by the responsible ‘design and build’ contractor. The described innovative developments followed the three axioms of the contractor: “Design and

build in one hand”, ”Integration of architectonic, structural and industrial design” and “Development of new and experimental products”. Respecting the wishes of the architect an intensive design and engineering course was followed mastered in the engineering department, co-ordinating Holland Composites and Solico Engineering as indispensable co-makers. The urge for new product innovation, courage, spirit of enterprise and a certain naivety (not to know on forehand what hindrances would come in the future years of development of the project) prepared the embedment of an engineering course with multiple degrees of innovation. During the entire process the design methodology as development for special components, consisting of 3 mains phases: • Design Concept, • Prototype Development • Production Preparation, as published by Eekhout [2007] were followed quite literally.

11. Technical Engineering and Prototype Testing After the first one year of experimental work and prototyping, the final ‘design & build’ contract was agreed on the basis of the adapted quotation and the approval of architect Safdie on the quality of the prototypes. The final engineering started on the basis of AutoCAD and Mechanical Desk Top. The final analysis incorporated: • Final production methods of the GRP wings, • Testing of the connections of the sandwich panels on delamination, • Assembly connections loading deformations, • Fire resistance • Logistics in the Netherlands, • Transport of the sandwich segments in special open containers, • Assembly of the segments on special moulds on the building site, • Jointing and finishing the wings, • Hoisting of the completed wings into position.

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After the prototype development phase of the first one year the final engineering inclusive prototype construction testing in the laboratory also took one full year. At the Israeli side approvals became very complex, however. Due to political change in government from the Labour party of Rabin to the Likud party of Sharon, all proposals were reviewed by the local government bodies with extreme attention, so that many unforeseen and sometimes unnecessary problems were detected by the governmental bodies and had to be neutralized by the engineering parties. Many people in Israel apparently did like to see the project uncompleted or stopped half way. This also led to the involvement of the two experts in the field of glass fibre reinforced polyester: two professors of the TU Delft, faculty of Aeronautics, prof. Adriaan Beukers and prof.dr. Michel van Tooren, who played an inspiring role in the Atomium recladding project, as mentioned in chapter 4. They were invited by the client (The Friends of the Rabin Center) directly to draft a second opinion on the supplied engineering and played their role in this project honourably.

Fig. 24-27. Birdseye and frontal views of ‘The Library’ and ‘The Great Hall’

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Fig. 28. Close-up of ‘The Great Hall’ wings with insert points for connectors to connect the wings to the columns and structure of the ‘central body’.

Fig.29.Five sections of ‘The Great Hall’

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12. Prototyping, Production and Installation After two years, in January 2005 the go-ahead was given for production. From that time onwards the production of the composite segments went into operation. Hence the third project year of production and assembly started with the experimental production of the components on the negative moulds. It was decided that production would start with the smaller roof of the Library, although the client had in the back of his mind only eventually to build the Great Hall, just in case the costs of the sandwich construction operation would be too high. So seen from the learning curve in the production development, the very production of the two smaller roof wings of the Library was taken up first. The production technique used in this case has been taken from standard production techniques of producing sailing ship hulls as Holland Composites had produced its integral mono-hull ship hulls. The base of the vacuum injected production was a good point of departure. In case of the sandwich wings the second dimension in the largest wings of 30x20m (compared to the 30x5m boat hulls) and the impossibility to sail the completed wings independently to the site like a sailing ship, proved to be a major experimental level for the GRP production. It was decided that the entire wings would have to be produced in more or less rectangular segments, to ship them out stacked in containers and to assemble them in the form of the completed wings on site and hoist them in as wings finally. This had as a consequence that the segments had to be produced individually in their deconstructed shape of one-off forms. Each segment form was different. All segments had a different form and some had long asymmetrical points. The shrinking of these segments after curing of production proved to be an unforeseen adventure. Shrinking of each segment appeared asymmetrical, always in another direction and during production one could wonder how all of these twisted panels could lead to a smooth form. Unusually for the co-maker the production proved to be necessarily very engineering intensive. The foam blocks of polystyrene had been milled accurately by Marin bv, specialised in moulding ship models for hydraulic testing, to negative moulds from CAD/CAM files. After the milled moulds arrived at Holland Composites, the surface was first topped with an epoxy skin to work on, and then covered with a plastic foil. In the vacuuminjection procedure glass fibre is impregnated with polyester resin by sucking the plastic envelope around the fibre weaves and foam core blocks vacuum and by feeding polyester from the other side to enter into the cavities of the construction: in the fibre weaves and between the foam blocks. Since the resulting layer of GRP at the mould side describes the desired form of the roof in the best possible way, this side had to become the upper layer of the roof. From the prototypes it was concluded

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that the segments had to be produced top down: the upper surface needing the most accurate form in the opinion of the architect as the sun would shine over the upper surface and always would result in tangential rays over the surface. Hence all regularities would ruthlessly be visible. Less so on the lower side with its indirect day-lighting. So the upper surface had to be made on the mould side and the lower side would have to be made as the top layer and hence a little less accurate and flush. The fire proofing tests resulted in an extra internal layer of gypsum rich finish, which would heighten the fire proofing characteristics of the inner face of the wings to the required level. This implicated that the inner face had to be smoothened after assembly any way. So production with the upper surface at the mould side was the consequential procedure. It was also decided to pre-cure the top layer as a single layer of fibre weaves with polyester resin before vacuum injection of the complete package of the segment construction. After the top layer of resin soaked fibre was cured, the core of fire-resistant polyurethane blocks was sawn and arranged to the roof layer. Between these foam blocks long glass fibre strips were placed in vertical position to act as stringers between the upper and lower skins. These stringers are the structural ribs in the sandwich as a replacement of the original steel structure or as a stiffening of the sandwich composition, which appeared to have too much flexibility for the roof structure. Tests and analysis had resulted in the introduction of these stringers to lead away the shear forces in the construction package. Due to results of the performed accelerated long time tests delamination could occur at the most critical points: at the supports of the columns, between the internal spans and the cantilevers. A similar problem and loading occurs ate the attachment of an airplane wing to the fuselage. The core foam blocks were subsequently covered with the lower set of glass fibre weaves to form the bottom skin of the segments and an enveloping foil for the next vacuum-injection. The polyester resin that was consequently injected between the blocks, forming the GRP glass fibre strips stringers, thus creating a structural connection between the upper and the lower skins. In doing so the function of the core blocks had dramatically changes. From the original shear layer, they were now only functioning as ‘lost internal moulds’ for the lower surface of the wings. Its function was also foreseen as a stiffener of the upper surface to ensure that a solid backing is available behind the upper skin if an unfavourable local load was to occur on the outside of the upper roof skin. Local buckling of the GRP sandwich is prevented in this set-up.

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After production of the first three roof segments of the Library, a mock-up was installed at the premises of Holland Composites. The segments were placed on a temporary supporting jig structure in order to fit all the segments, to connect them structurally and to smoothen the final layers in order to prove to the manufacturing team, the engineers , the architect and the client respectively that the wing-shape would have the desired fluent shape without any irregularities. This mock-up was built in March 2005. After a site visit of the architect, and with his approval, the full goahead for the production was issued. The remaining segments of the Library wings were produced in the above described production sequence. In May 2005, around the time of the first congress of Delft Science in Design, the two wings of the ‘Library’ were shipped to Israel in specially designed super-crates, sized 3,5m x 3,5m x 15m in volume to contain as many segments possible in stacked position in a specifically designed order. Transport was foreseen in 5 lots of the 5 different wings via regular freight ships to the harbour of Ash Dod and from there on to the site by inland trucking transport. Parallel to the production of GRP segments in Lelystad, the production of the steel columns and the rotating column heads had commenced in Delft. Next to the load bearing function towards the roof these columns also bear the deadweight and wind load of the frameless glass façade. Production of the columns appeared to be a routine job, the only difficulty being the connection between the columns and the roof. All columns had different 3D angles and the sandwich construction was quite weak on the positions of the supporting columns so that a danger of punching the column supports through the sandwich was analysed. Hence during the production of the GRP segments at Holland Composites steel plate inserts parallel to the lower surface of the wings were placed within the sandwich to be able to connect the steel upper plates of the ball joint column tops to the sandwich construction without perforating the wing. Specially developed ball-and socket-connections on top of the columns were designed to accommodate the very different corners of the supporting points under the lower skins of the wings. The ball joints had to be bolted to the inserts. A large challenge for the steelmakers proved to be the central body: the central part of the ‘Great Hall’. Due to the large forces from the upper and the lower roof wings amongst others, this part of the roof has to cope with, unfortunately a tubular steel space frame was the only solution to make this span under this loading possible. The result was a complex space frame structure of tubular steel, later to be fitted with thin GRP panels at the top (roof surface) and bottom (ceiling surface). Because accurate 3D rolling of tubular elements is a rather complex procedure, the entire composition was made in 2D rolled tubular segments, which pos-

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sessed a greater accuracy. The 3D tubes, mainly situated in the length of the central body, at best approaching the desired shape, therefore had to be connected to the accurately shaped 2D tubes. At the premises of Holland Composites the entire central body was assembled in order to fit the panels. The structure appeared to be as high as 8m, which was very labour-intensive for the erectors. So after the trial assembly in Lelystad, it was decided to build up the final assembly on site in Tel Aviv in two halves, which would result in a building height of only 3 m. After the panels were trial fitted on the particularly engineered and positioned stool supports, the structure was disassembled en transported.

. Fig. 30-38. Milling machine at Marin (30), scale model of upper wing of ‘The Library’ (31) and production of the roof segments at Holland Composites (29-36). Vacuum injection of the top layer on foam block milled by Marin (32). Insert to be placed in the GRP sandwich roofs in order to make a connection between the roofs and the columns (33 & 35). Placement of foam blocks and glass fiber mats, which will become stringers (34). Vacuum injection of the bottom layer (36). Final result, in this case an early prototype (37). Discarded foam moulds (38).

After the production of the roof segments of the lower wing of the Library, discrepancies between the theoretical drawings and the practical distortions and tolerances from shrinking of the polyester resin in the enveloping vacuum bags were measured. Tolerances because of warping of the negative moulds resulted in unforeseen deformations of the produced

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GRP components. These components together had to form the ruthless smooth surface of the complete wing in the end. All aspects were approached in an engineering manner: measuring, analysing problems and deducting solutions. Analytical engineering in the best traditions of the TU Delft made the initial amazing, improbable design solution finally a reality. The resulting design is a combination of structural design with a strong architectural flavour, incorporating the technologies from aeronautics, ship building, industrial design and geodetic surveying. It poses an example of multiple innovation of technology.

Fig. 39-40. The central body of the Great Hall (spanning ca. 30m)

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Fig. 41-42. Roof segment (left) and fitting of all the roof segments of the lower wing of ‘The Library’ at Holland Composites in March 2005.

Fig. 43. 3D drawings of the roof segements in 4 special transport containers

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Fig. 44-45. Building site in Tel Aviv zoomed in on ‘The Library’ with the truss and columns already installed (left). Open container at Holland Composites with the roof segments ready for shipment in April 2005Holland Composites in March 2005.

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13. Assembly, Tolerances and the Neutralization Regime Due to the experimental character of the production process and the initial unfamiliarity with the consequences of vacuum deformation, it was decided to perform a test-assembly or pre-assemblage on the premises of Holland Composites in Lelystad of all the wing segments. The fitting took place on a positive steel frame, the shell would therefore be curved upward. One of the conclusions was that we would assemble the wings inversely, so the downward curve would face upward. When a technician would fall, he would fall in the shell, instead of falling off the shell. Subsequently the shell was turned over with a mobile crane, by means of three temporary hoisting fixtures in the shell. From the pre-assembly conclusions could be drawn regarding the theoretical versus the practical measurements of the individual segments. All segments were produced on individual foam moulds and they all had their own shrinkage and shrinkdirection. Yet together, these segments were required to form the unforgiving smooth surface desired by the client and architect. It was noted that the total fitting of the individual deformed segments would still form a smooth surface when the entire shell was assembled. In order to acquire this smooth surface a solid frame was needed with clamps in order to force the segments in the desired position. In general the segments proved to be somewhat smaller than intended. They had shrunk because of the vacuum injection, causing the seams to be 2025mm, instead of the anticipated 12-15mm. When filling up the seams during assembly a bigger seam meant more fibre and more resin (due to the required ratio between fibre and resin) and thus causing a larger weight of the shell. The connections between the individual segments can be divided in connections in the length and connections in the width of the segments. Both have a structural function. On the side of the segments a rabbet has been made of 220mm with and 15mm depth. In this rabbet a prefabricated reinforcement strip of 200mm width and 10mm depth (of high density glass fibre weave layers that had been vacuum injected with resin) was placed. This reinforcement is glued and clamped by screws for curing purposes only. After the segments of the two wings in Lelystad were fitted on the steel frame, controlled and approved, the segments were dismantled and shipped in the special containers. The assembly on site had to take place on the south side of a tall wall on ground level. The segments were assembled inversely, measured, connected by the prefabricated reinforced strips, measured again, touched-up and finished with the structural reinforcement meshes and filler. The lower side with a fire retarding layer, the upper side with a infrared light resistant layer. Next, the shells were turned over and identically finished on the other side. After the hoisting onto the Library, the first shell wing was positioned on a steel flat truss

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sub-structure, which in its turn rested on a concrete wall with a much larger tolerance difference. Positioning directly from the crane onto the column heads, or wingconnectors with its adjustable shaft and connection plates, could only take place accurately by following the theoretical drawings. Until the end of the assembly and erection theoretical drawings remained the decisive factor. In all phases of engineering, production, assemblage up until the hoisting and positioning theoretical drawings were always present and compared, as this was the only assurance that at the end the wings would fit into position. Neutralizing different components is a adventure in itself. Building parts were simultaneously produced in locations all over the world. In this project the steel was manufactured in Delft, the glass in Luxembourg and Belgium, the polyester segments in Lelystad and the concrete works in Tel Aviv. The concrete had the biggest tolerances, up to 100mm. The seams of the roof segments measured theoretically 12mm, in reality 25 to 30 mm and the seams between the glass panels a more accurate 8 to 12, average 10mm. And all these different tolerances have to be neutralized in their principle detail design (allowing neutralizing at all). Tolerances in the different stages from design, through engineering to prototyping, production and building on site govern the success of each prototypical Free Form project. The geodetic supervision during the process of production and installation has grown in its importance since Blob structures for Free Form architecture had to be realized. Having arrived at this point, one has to remember that the success of Henry Ford in the automotive industry was not the running belt. “Ford’s

1908 Model T was his 20th design over a five year period that began with the production the original model A in 1903. With his model T he finally achieved two objectives. He had a car that was designed for manufacture, as we would say today, and also was, in today’s terms, user-friendly. Almost anyone could drive and repair the car without a chauffeur or a mechanic. These two achievements laid the groundwork for the revolutionary change in direction for the entire motor-vehicle industry. The key to mass production was not – as many people then and now believe – the moving or continuous assembly line. Rather it was the complete and consistent interchangeability of parts and the simplicity of attaching them to each other. These were the manufacturing innovations that made the assembly line possible” [From Womack et al, The Machine that Changed the World:5]. In similar projects where buildings with Free Form design had to be realized (for example: Town Hall, Alphen aan den Rijn, see www.mickeekhout.nl), the total costs involving geometrical surveying from prototyping and productions up to assembly and installation the costs were as much as 3% of the contractual turnover: a serious amount of man hours. The building industry has finally arrived at the international industrial level of 3D design of components, boosted by the inevitability of

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the technical compositions of Free Form architecture. From now on the different ingredients or components of free form architecture that are made in lots by different co-makers / subcontractors, sometimes in many countries all over the world for just one project, put the building industry in line with the automotive industry, only 100 years later. This is helped by the change-over from the concrete and bricks technology where joints always can be adapted locally, to the more industrial (factory manufacturing) metal and mid/high-technology where all components have to be fitted specifically in an industrial mode, so with outspoken and very accurate tolerances only. Once Henry Ford could force his components suppliers to produce and supply components with fine and accurate (and only negative) tolerances, he could avoid the adaptation of components on the assembly floor (in the building industry: on the building site). This made the difference between the former automobile ateliers where cars were hand-fitted after most of the time was lost in refitting the components and an industrial and almost ‘blind’ assembly only focussed on the assembly activities and not any more on the component care. From that moment on, Ford could even employ a running belt as the continuous production base of assembly-only.

Fig. 46-47. Preparation and hoisting of the upper and lower wing of the Library in August 2005

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Fig. 48-49. Assembly of the roof segments by gluing and bolting glass fibre polyester plates on the seams before applying the finishing layer

The glass facades were developed separately form the roof wings. They were based on more than a decade of experience with designing and realizing of frameless glazing. The original design was a standard mullion façade, which was redesigned as a frameless glazing façade. The architect required a specially fritted glass in order to influence the daylight penetration and the solar entrance. This part of the building was not as interesting scientifically.

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Fig. 50-51. View of the building site on the 6th of November 2005, photographed by Ardon Bar Hama.

Fig. 52. View of the building site in April 2006.

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Fig. 53. The Library – Interior view

Fig. 54. Overview of the building site just after completiont of the roofs by Octatube.

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Fig. 55. Finishing of the top layer of the roof by “airborne builders”

Fig. 56. The Great Hall Interior view

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14. Carbon Fibre Blob Shells, as Yet One Bridge Too Far The above described sandwich construction shells of the Rabin Center form a renaissance of the shell structures of the 1960’s. In those days, due to simple mathematical hand calculations shells were thin, followed the ideal spherical, conical, cylindrical or hyperboloidal forms. Results were mostly 50 mm thin concrete shells with only one central reinforcement layer of steel bars. Many shells had an Hispanic origin: Eduardo Torroja, Spain, and Felix Candela, Mexico were the prominent pioneers. The shells were built in countries with high material and low labour costs. In the 1970’s the pioneer’s retired and the concrete shell fashion stopped. Crafted carpenters retired after that and nowadays making a concrete shell would again become an experiment. Heinz Isler from Switzerland built his concrete shells with re-usable timber moulding on scaffolding in the 1980’s. He also retired and closed his company. These concrete shells have now to be designed in open en direct collaboration between architect en engineer.

Fig. 57–58. Works by Felix Candela: a mould for concrete (left) and a prototype for a cantilever made of concrete (right)

Blob architecture emerging in the late 1990’s (Guggenheim Museum Frank O. Gehry, 1998) changed these conditions, as the architect designs either directly in models or on the computer as if he is a sculptor. The dramatic 3D effect dominates architectural thinking. The structural designer has not an equal position, but is asked subsequently after the architect has found out a model or geometry, which suits him out of visual design considerations. Alas there are usually no direct feedbacks, no improvement feedback loop from structure to architecture. That is to say the engineer has to realize the sculptural whims of the architect to a trustworthy architectural structure, safe in use. This has as a consequence that the form of the new generation of shells are much more arbitrary in structural sense and hence have a more unfavourable structural behaviour.

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Fig. 59. Guggenheim Museum Bilbao, architect: Frank Gehry

Many of these new shells are now governed by bending moments due to their unfavourable form and supports, rather than by normal forces and shear forces in the plane of the shell as in the first generation of shells. The constructional solution of the new generation of composite shells is in principle the one developed for the Rabin project and now the system solution: a double stressed skin sandwich composite construction in free form with a structural core. The two skins enable bending moments to be taken, caused by unfavourable loading conditions, column or support positions and, structurally speaking, arbitrary or rare shell forms. We would still call these roof forms ‘shells’ as a reminiscence to the thin-walled shells from the 1960’s, but mathematicians and methodologists suggest to invent and publish a new name. The answer is: Blob-shells or Free Form shells. The next step in development is caused by the differences in loading behaviour between conventional structures in steel of concrete and glass fibre reinforced polyester shells. Blob shells, made of glass fibre reinforced polyester are usually much more flexible, and cannot reach the stiffness and rigidity of conventional structures. For sailing yachts, often prestressed by its masts and riggings, rigidity is a relative connotation. As long as the doors and cupboard doors still close and open only a few sailors would mind the distortion in the hulls of their yachts. The consequences and joys of trimming in speed govern. However, buildings components like windows and doors, often have vulnerable, annealed glass components directly attached to the roof structure. These are influenced by the stiffness of the load bearing structure. Depending of the details,

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this requires the engineer’s attention. Cantilevering blob-shells are more flexible than in conventional structure. The cantilever of the tip of the largest wing at Rabin was analyzed as 100mm upwards and 210mm downwards. The total sandwich thickness was 314 mm. This fits in the general shell theory of Thimoshenko, so that this composite shell still behaves as a shell. Alternatives in steel and in concrete were analyzed to show deformations of 200 respectively 100 mm only. The engineering line-of-thought was that, as long as the movements of the roof under loading do not cause brittle fracture, de-lamination or other handicaps in the blob-shells internally and as long as the flexibility of the blob-shell does not lead to problems in the technical composition of the building around the blob-shells, for example by crushing glass panels or causing leakages due to too much movements in the silicone joints, a larger movement would be acceptable. So no rules yet, but intelligent and responsible building technical engineering, characterizing the experimentation phase. The standardization and normalization phase of newly developed technologies will follow after 5 tot 10 years only. But new projects involving blob-shells in future will show up with no doubt more strict requirements as to the anticipated deformations in GRP. Other materials are interesting in this respect as well. Epoxy and carbon fiber is the alternative usually employed in the production of high-tech sail yachts. The next generation will probably be blob-shells in carbon fiber reinforced epoxy. This material is much more rigid, does hardly expand as the modulus of elasticity of carbon fiber reinforced epoxy is much lower than that of glass fiber polyester. However, these advantages are accompanied by a much more strict production process including curing in a tempering oven, which limits the sizes of components. For transfer of technology from the yacht building industry (for example used in the black and white ABN AMRO yachts of the Volvo Ocean Race 2005/2006 were built in Lelystad NL using this technology in vacuum injection), the costs play an important role. As the thresholds in the building industry are quite low and the price of carbon fiber reinforced epoxy shells are high, clients could prefer to go back to reinforced concrete after studying the price of carbon fiber epoxy shells. Yet amongst architects a strange mechanism works: the ‘first-of-the-block’ effect. The first guy of the block who buys a pink Cadillac is celebrated, the second one is a looser. So at least he has to buy himself a Cadillac of a different colour. Moshe Safdie designed shells that were realized as white shells in original material. The next architect would prefer a black shell to distinguish himself or herself. In this case the famous London-based architect Zaha Hadid designed a Free Form Mediateque in Pau, France, near the Pyrénées. Her initial design images show the ‘Mediateque’ in white, but the tender documents of 2005 show now a black design with carbon fiber as the basic material.

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In the development of the Mediateque tender design in the proposal of the author, accompanied by co-makers in the Netherlands and England, the idea was production of the segments of the carbon fibre epoxy blob shell segments locally in a temporary factory shed, a re-assembled curing oven, next to the site. The process of tendering did not allow for any prototyping on the side of the client or architect. Rather this extremely experimental project was tendered as a standard building project. The resulting tender price was 4 times that of the client’s budget and, may be as a blessing in disguise for this extremely experimental project on a giant scale, the project champion, Pau’s mayor André Labarrère, who wanted to realize his ‘8ième Grande Project’ died the day before the tender date. The project was cancelled. The design drawings indicate the design proposals in carbon fibre epoxy blob shells, which will probably be illustrated in a next Delft Science in Design conference at TU Delft if the experimentation course could be continued.

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Fig. 60-65. Preliminairy engineering drawings of the Mediatheque in Pau by Octatube

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15. Conclusion The resulting design in this contribution shows that building technical design can lead to an integrated and innovative process. In such processes many disciplines are collaborating and have to be co-ordinated throughout the entire process inclusive all of its unforeseen and experimental stages. The results of this process have to be integrated into one technical artefact that satisfies all requirements and gives efficient answers or compromises in all of its life phases, be it conceptual design, material design, detail design, engineering, productions, assembly, installation, loading behaviour, functional use as a building, meaning of the artefact as a building, (even as Architecture) and in its (global) context/surroundings, in its meaning as integral part of the building. Society expects perfect solutions from scientific designers. These solutions are not only the functional and technical solutions. It may be true that the well-known restrictions in the volume prices of the building industry, as posed by the clients in the building industry, lead to traditional and wellknown technologies. Yet the thresholds to enter the building industry are low and competition is fierce. Sometimes experiments are persistent, initiated by technical designers who are willing to wander though the entire experimental development process and are able to analyse and solve all foreseen and unforeseen problems. It requires an experimental mind set. In this case the interdisciplinary collaboration from Architecture with Industrial Design Engineering, the Maritime Engineering and Aeronautical Engineering proved to be essential and an enrichment in the field of Architecture in order to introduce the renaissance of the shell as ‘Blob shells’ of ‘free form shells’ for the world.

References [1] Beukers, A., (2003), Licht. lichter, lichtst: lichtheid als gedachtengoed, Delft. [2] Eekhout, M., (2007) Product Development and Component Design, Multi Science Publishing, London [3] Kohn W., Rowe, P., Rybczynski, W., Goldberger, P., Sorkin, M., (1996), Moshe Safdie, Academy Editions, London [4] Tooren, M. van, (2003) Sustainable Knowledge Growth, Delft. [5] Womack et al, (1996) The Machine that Changed the World, Harper Perennial, New York, ISBN 0060974176

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Delft Science in Design 2 M. Eekhout et al. (Eds.) IOS Press, 2008 © 2008 IOS Press and the authors. All rights reserved.

Design in the Chair AeroSpace for Sustainable Engineering and Technology (ASSET) Joris Melkert 1

Assistant professor, Delft University of Technology, Faculty of Aerospace Engineering, Delft, The Netherlands Abstract This paper gives an overview of the design work being performed in the chair Aerospace for Sustainable Engineering and Technology. The research of the chair is focusing on the themes sustainable energy conversion and sustainable transport. The work of the chair is organized in projects. For both research themes this paper gives an overview of two projects each. Key words: design, sustainability energy conversion, transport

1. Introduction The chair Aerospace for Sustainable Engineering and Technology was started in 2003 by professor Wubbo Ockels. The chair aims at applying hitech technology from aerospace for sustainable development. The chair does this from the vision saying that nature has no mercy and that humanity in the future needs to play the game with nature, rather than against nature. In this process technological means are essential, and in particular the technologies developed in the field of aerospace engineering can play an essential role. It is in this respect that ASSET sees an opportunity, namely to initiate activities where the capabilities and results of aerospace engineering are particularly used for sustainable developments. As this field is new, no previous experience existed. The strategy proposed was to initiate a number of highly visible and relevant topics that will lead to subjects for education and further research. The Faculty of Aerospace engineering strives towards organizing its research and education in an object oriented way. In fact for ASSET the objects are formed by highly visible, challenging and stimulating projects from which the education and research forms a spin-off. The research is both applied and fundamental. This policy fits in the general approach of the Aerospace Faculty and has proven its merits in the past making the faculty very successful. The two main research themes are: 1. Sustainable energy conversion

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2. Sustainable transport The most visible projects in each of the research themes are Research theme 1 - sustainable energy conversion • Ladder mill • Kite propelled ships Research theme 2 - sustainable transport • Nuna solar cars • Superbus This paper will focus on the description of the projects and design related aspects. The paper will not focus on the societal and economic impact and viability since this is considered to be outside the scope of this paper.

2. Ladder mill The Ladder mill is a concept to harvest electricity from high altitude winds. The concept’s operating principle is to drive a ground based generator using a series of kites. Several kites fly high in the air at altitudes of more than one km. All kites are connected to one single cable that connects to a drum in the ground station. The lower part of the cable is wound around this drum. A generator is connected to this drum. When the kites fly in kite mode they develop a relatively large lifting force with which they pull the rope from the drum, which in its turn drives the generator and thus creates electricity. At the top of the cycle the kites change to a glider like flying mode. In that configuration they generate substantially less lift and can be reeled in using relatively small amounts of energy. At the end of the cycle the kites again change to the kite ode and start pulling again. This cycle produces net energy.

Fig. 1. Principle of the Ladder mill with ground based generator (source: Bas Lansdorp)

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Fig. 2. Artists impression of the Ladder mill (source: Jeroen Breukels)

The forces acting on the kites in the two flight phases can be best illustrated using standard airfoil theory. The following two figures show the two basic flying conditions. The first figure shows the kite mode. The second one the glider mode. In the kite mode the design should be made such that the net resulting pulling force created is high. In order to be able to achieve this the lift force has to be considerably higher than the weight of the kite. Next to that the drag force has to be as small as possible since that has to be compensated by a forward component of the pulling force. The larger the component of pulling force in forward direction has to be, the more area the Ladder mill will need. Thus the ratio between the lift and the drag has to be maximized while the weight of the kites has to be minimized.

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Fig. 3. Kite flying in kite mode (source: Bas Lansdorp)

Fig. 4. Kite flying in glider mode (source: Bas Lansdorp)

In the glider mode the pulling force in the rope has to be minimized but may not become negative. Therefore a small resulting pulling force will be required. In this phase of the flight the weight will be helpful in moving the kite down with as little pulling force as possible. The mass of the cable also has an effect on the performance of the system. Since he Ladder mill consists of a series of kites the pulling force increases with an increasing number of kites of the same size. The pulling force will be lowest between the top two kites and will be highest between he lowest kite and the ground station. The cross sectional area of the cable can be adjusted for this. As a result the mass of each cable segment will change as well. In optimizing the configuration this can be taken into account as well. The amount of energy is depending on the number of kites, the design of each kite and the wind at altitude. The wind speeds change considerably with altitude. While wind speeds at altitudes below 100 m are rather unpredictable the wind speeds at higher altitudes are more predictable. The following figure shows an overview of average wind speeds as a function of altitude in the Netherlands.

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12

10

Altitude (km)

8

6

4

2

0 0

10

20 30 Wind speed (knots)

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Fig. 5. Average wind speeds over altitude in the Netherlands (source: Royal Dutch Meteorological Institute)

The figure shows that the wind speeds increases rather rapidly when moving out of the boundary layer of the Earth. At altitudes above 1 km the wind speed changes gradient and keeps increasing until an altitude of approximately 10 km is reached. The design of the kites can be based on a number of concepts. Within the research program two main designs are under consideration. The first is the surf kite configuration as shown in the following figure. These kites are well known for their ability to generate large pulling forces and controllability. In general the mass of these kites is relatively small and they are controlled by at least four wires, two on either side. Manual control is the normal way of operation. The lift to drag ratio of these type of kites is significantly smaller than that from aircraft.

Fig. 6. Example of an inflatable aircraft like kite (source: Jeroen Breukels)

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Fig. 7. Standard surf kite (source: Bas Lansdorp)

The second approach in the design of the kites is the aircraft approach. Kites can be seen as towed aircraft. In towing gliders this is being done on a regular basis. Towing an aircraft will have consequences for its stability. Aircraft in general can reach higher lift to drag ratios than kites. On the other hand the mass is also higher. In the development program therefore aircraft like structures are being considered but they are being designed as inflatable structures. One of the factors of primary importance is the control of the kites. Therefore much effort is being put this. The practical part of the research now focuses on control designs of surf kites. The theoretical part of the design focuses on control of aircraft like kites as well. In the control of surf kites a system has been designed in which the control can be performed by two instead of four control wires. One wire on either side of the kite is being moved along a rail. It has been demonstrated that accurate computerized remote control is now possible. Another part of the Ladder mill project is focusing on he design of the ground station. In this ground station the drum and generator have to be located. Depending on the power being generated the size of both the drum and the generator change. Design requirements of the ground station include issues like controllability, mass and efficiency of the generator being used. The following figure gives an overview of the current design of a 3 kW ground station which is currently undergoing testing.

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Fig. 8. Surf kite control by two wires only (source: Bas Lansdorp, Richard Ruiterkamp)

Fig. 9. The 3 kW ground station (source: Bas Lansdorp)

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3. Kite propelled ships One of the more recent developments is the application of kite propulsion on ships. Next to aircraft, ships can be considered as one of the most difficult means of transport to shift towards sustainability. The main reason for this that for the majority of their journey there will be no energy supply station nearby. This makes it impossible to propel them by electricity since the battery capacity would require too much space onboard. Nowadays the main source of energy is heavy fuel oil. One possibility would be to look at the use of wind energy conversion systems. On the oceans there will be wind power available quite often. This could be used for propulsion. Traditional sailing using tall masts will most probably not be an option for commercial shipping but kite like propulsion devices might become feasible. The German company Sky Sails is currently developing systems like this.

Fig. 10. Artists impression of the Ladder mill ship sailing into the wind (source: Jeroen Breukels)

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Fig 11. Applying a kite to a ship (source: sky sails, Germany)

The ASSET chair is looking into the possibility to apply the Ladder mill technology to shipping. The potential benefit of this would be the possibility to use the kite system for generating electricity. This electricity then powers the engine of the ship or can be stored in an onboard battery pack of limited size. Theoretical research has shown that it would be possible to use this concept not only to propel the ship in tail wind conditions but also in head wind conditions. The following figure gives an artists impression of a Ladder mill powered ship. Currently research is being performed in developing a demonstrator.

4. Nuna solar cars The most well known project of the ASSET chair is the series of NUNA solar cars. The Nuna solar cars were developed for taking part in the World Solar Challenge in Australia. This World Solar Challenge is a race from Darwin in the North all the way to Adelaide in the South of the country. The race has a length of 3021 km and normally takes place every two years. The race was first held in 1987. The first Nuna car took part in the 2001 race. During the race the use of solar energy is the only source of energy allowed. The cars do have limited battery capacity but they are not allowed to recharge them other than using solar energy. The race is a multi day race. Racing times are between 8 am and 5 pm. The available solar light during the remainder of the day may be used to recharge the batteries.

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The size of the solar cars is limited such that they fit into a 5 m long x 1.8 m wide x 1.7 m high box. For the race editions up to the 2005 race the amount of solar cells was not limited. During he 2007 race the amount of solar cells was reduced to 6 m2.

Fig. 12. Overview of the World Solar Challenge route (source: WSC)

Fig. 13. Nuna 1 solar car

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The Nuna 1 team approached professor Ockels in 2000 for his help. They developed a solar car which was designed using aerospace technology as much as possible. The aerodynamic design played a major role in he design of the whole car. The design was made such that the drag was minimized. Next to that the structural design was based on a light weight truss covered with the aerodynamically shaped outer shell. The leading edge of the vehicle was made rounded such that cross wind conditions would not have a detrimental effect on the performance. Next to that a computer based race strategy was designed such that the speed of the vehicle was optimized using he available light, the expected available light and the state of charge of the battery pack. The strategy algorithm was based on genetic optimization. This resulted in a winning performance where the average speed was 92 km/h. This speed was considerably higher that previous cars had ever achieved. Nuna 1 was the first car to finish the race within four days. Nuna 1 was considered an outsider. The alleged winner was the Australian solar car Aurora.

Fig. 14. Nuna 1 (driving on the right) overtaking the Aurora solar car (on the left)

After he success of the Nuna 1 a new team started the development of a new car in 2002. It was decided not to optimize the previous Nuna but to start from scratch since there were too many areas in which he design could be made better. The result was the Nuna 2 which became a car with a full carbon fiber epoxy composite body. The truss structure used in Nuna 1 had been considered too heavy and therefore not used anymore. The aerodynamic design was changed in the sense that the top view showed a more square car. This would give more area for placing solar cells. The expected detrimental effect of cross wind had not occurred and

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therefore this more square design could be applied. The result was an even faster solar car which again managed to finish he race within four days, now averaging a speed of 97 km/h. The Australian solar car Aurora came in second again. However their average speed was already higher than that of Nuna 1.

Fig. 15. Nuna 2 solar car

Fig. 16. Mission control vehicle

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In 2004 it was decided to take part in the 2005 race as well. The organization had decided that it would move the race more towards the Australian winter. It had decided so because they were afraid of the high average speeds the cars had reached in the last two editions of the race. The 2005 race would take place in September. The new Nuna team decided to start all over again with designing a new car. All aspects of the care were redesigned where again aerodynamics, structural weight and control strategy formed the major design areas. The aerodynamic design was changed such that the cockpit was moved aft. This created a larger area of undisturbed flow. The attachment of the solar cells was made such that a large part of the top surface of the vehicle could operate in laminar flow conditions. Research was also performed in the area of boundary layer suction. Although initial test results were promising it was decided that this technology came too early and was not mature enough. Eventually the researcher who performed this research started his own company in laminar flow control for the automotive sector. Another aerodynamic design change was the design of the two front wheel fairings. Since in the period of the race quite some cross wind was expected the design was changed such that the vehicle could benefit from this. The shape of the fairings was made such that in cross wind conditions they would start acting as sails. They would create a forward force contributing to the thrust of the vehicle.

Fig. 17. Wind tunnel model of Nuna 3

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Fig. 18. Flow visualization tests on Nuna 3

The structural design was changed in the sense that the body was made as light weight as possible. Nuna 2 had made the step towards a full carbon body. The structural method applied was that of a sandwich structure over the whole of the body. This resulted in a strong and stiff body, also in places where this strength and stiffness was not required. The body of Nuna 3 was designed such that the center part was shaped like as a sandwich monocoque structure. The remainder of the body was made out of a thin carbon fiber laminate without the sandwich core material. The race took place in September. This meant that there was more low incoming solar radiation. Therefore not only he top surface was covered with solar cells, also the side panels were covered with solar cells as much as possible. In the control system a fully remote cruise control was incorporated. This had been tested in the Nuna 2 after he 2003 race had taken place. In principle the driver only had to steer the vehicle. The speed of he vehicle was optimized by the control strategy software and then fed into the cruise control of the vehicle via remote control. In the end this resulted in a winning average speed of 103 km/h.

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Fig. 19. Nuna 3 during qualification trials in Darwin

The regulations for the 2007 race have changed considerably. The maximum area of solar cells allowed has been reduced to 6 m2. Furthermore it is required that the driver sits n an upright position. Where the drivers in Nuna 1, 2 and 3 more or less were lying down the driver in Nuna 4 may not lean back more than 27 degrees. Next to that the steering control must be performed by a steering wheel. The sliding control sticks used before are banned. Finally the vehicle must have a roll bar to protect the driver in a roll over situation.

5. The Superbus The Superbus is a concept for a streamlined electric vehicle, which can operate at cruise speeds of up to 250 kilometers per hour. Such speeds can be reached on special designated tracks, but the Superbus can also be driven at lower speeds on existing roads and bus lanes. Professor Wubbo Ockels has invented the Superbus concept in 2004. The ASSET chair is now designing and building a full scale demonstration vehicle. This demonstration vehicle is to be displayed at the 2008 Beijing Olympics.

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The Superbus combines Aerospace Technology and Information and Communication Technology (ICT). The Aerospace technologies included are: •

low drag design

•

light weight design

•

aviation levels of safety

•

aircraft control

•

aircraft reliability

•

The ICT technologies included are

•

detailed knowledge of the road

•

accurate navigation

•

surveillance radar

•

flexible logistics

Fig. 20. Front view of the Superbus

General description With a length of 15 meters and a width of 2.5 meters, the Superbus has similar dimensions as a conventional bus. Due to the seating arrangement without a centre aisle however, the height is just 1.7 meters. Instead of a few large doors, 8 doors are placed along both sides of the vehicle to allow direct access to all seats. The seats can be arranged such that compartments of 2, 3 and 5 passengers are created. This reduces the frontal area of the vehicle. This is combined with a highly streamlined body shape resulting in a coefficient of aerodynamic drag of approximately 0.3, compared to 0.6 for a conventional bus or around 0.35 for an advanced passenger car. The combination of a low drag coefficient and a small

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frontal area result in a low aerodynamic drag force. The low aerodynamic drag makes the Superbus more efficient than a passenger car. The energy use of the vehicle at 250 km/h is the same as a normal bus would have at 100 km/h.

Fig. 21. Side view of the Superbus

The Superbus has three axles with a total of six rubber-tired wheels. The Superbus will be electrically driven. For this the Superbus will use a set of onboard Lithium-Polymer batteries. The Superbus will be operated by the combined use of a driver and electronic guidance of the vehicle. For example a radar system in the front can detect obstacles up to a few hundred meters down the road and accordingly brake or steer the vehicle to avoid a collision. Lateral guidance will also be provided with the use of radar technology. Propulsion The Superbus will be driven electrically. This makes it possible to control the emissions of the vehicle. In some situations emissions are not desired, like in inner cities. In that case electricity will be taken from the onboard batteries like hybrid cars do. Electricity can be generated using sustainable sources like sun and wind. Today’s battery technology allows a range of around 200 km. For long range performance an onboard generator will be required. This generator will be preferably powered using a bio-fuel. Possible options are bioethanol or bio-diesel. The electric motors used in the Superbus will be high performance, directdrive motors. The expected efficiency is around 95%. It is decided not to make use of in-wheel electric motors since they would increase the socalled unsprung mass. The unsprung mass is the mass of the wheels. A high unsprung mass has a detrimental effect on vehicle dynamics and passenger comfort.

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Infrastructure The Superbus can make use of existing infrastructure. It can drive in cities and on the highways. The length and the all wheel steering system make that it complies with current regulations such that is can pass roundabouts as well. When the Superbus starts driving at high speeds it must be separated from other traffic for safety reasons. For this a dedicated infrastructure is needed, called Super track. Since the Superbus is a lightweight vehicle the Super tracks can also be light weight. This has two benefits. Firstly the road construction can be relatively cheap. Secondly the building of the road has minimal environmental impact. This is especially important since in the traditional public transport systems half of the total environmental impact of a transport system comes from the building of the infrastructure. The other half is generated by the driving of the vehicles itself.

Fig. 22. Possible lay-out of the Super tracks

The road surface of the designated Super tracks can be heated during winter. This will be required for melting snow and ice. A possible way to do this is to make use of the so-called WinnerWay system. In this system the heat of the sun is collected in summer. This heat is stored in deep water layers in the soil. In winter this warm water is used to raise the temperature of the road to a level where the snow and ice melt. The concept has been tested successfully in the Netherlands. Making use of this method eliminates the need for spraying salt. This seems an expensive solution but in fact it may result in a lower total life cycle cost. Because the road surface has a more stable temperature throughout the seasons, the road surface will have a lower tendency to crack. Furthermore the absence of the necessity to spray salt reduces maintenance cost and the negative effects it has on the road structure are avoided as well. In this way maintenance costs will be reduced.

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Fig. 23. Winnerway heating system (source: Infratheker)

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Flexible logistics The Superbus is a transport system intended for distances above 30 km. In this way the best use can be made from its high speed potential. Applying the Superbus on shorter routes is possible but the high speed characteristics will not benefit the passengers in that case. The Superbus logistic system will be a demand driven system. In this respect it will deviate from the standard supply driven public transport. Instead of using designated stops, the Superbus can be ordered anywhere along the route. This system will most likely work via mobile phone or internet and can be compared by the booking of an internet airline. Multiple passengers can also order a row of seats or a separated compartment in the vehicle. The system will not be a door-to-door system. This would take too much time in the beginning and the end of the journey. The typical journey would start with the collection of passengers on a limited number of stops. The number of stops will have to be limited in order not to loose too much time in this part of the trip. After the passengers have been collected the vehicle will not stop anymore until the vicinity of the point of destination is reached. In this way the most benefit will be made form the high speed. At the end of the journey the Superbus will hold again at a limited number of points. The typical journey can be sketched as follows:

point of origin

point of destination Fig. 24. Lay-out of a typical journey

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Safety Safety is of prime importance in public transport. Therefore safety is an important issue in the design of both the Superbus vehicle and the Superbus transport system. Safety related to the vehicle has two aspects. The first aspect is the driver and the second aspect is the vehicle itself. It is chosen to make use of a human driver. He or she will be in full control of the vehicle. In inner cities and on highways he will drive the vehicle himself. On highways he will be supported by a number of advanced driver support systems. On the Super tracks the vehicle will be controlled electronically and the driver will have a supervisory role like the captain of an aircraft flown with the use of an automatic pilot. In principal the vehicle could be controlled electronically in all speed regimes but experience has shown that this is not always the best way. The reason for this is that traffic in inner cities can be rather unpredictable because of crossing children and animals. Next to that the driver also plays a role in the so-called social control. He or she will supervise the vehicle and make sure no vandalism takes place. Finally the issue of liability makes it more convenient to have a human driver controlling the vehicle instead of an electronic system. The vehicle itself will be supported by a number of advanced driver support systems. Research has shown that the safety increases significantly when the driver is supported by electronic support devices. Devices like these are under consideration at the moment. These systems will be radar supported. If demand is high enough, vehicles can safely operate at high frequencies of up to 7 seconds. On normal highways a safe interval between manually controlled cars is believed to be 2 seconds. When the Superbus drives at 250 km/h an interval time of 7 seconds results in an interval distance of approximately 350 m. This more than sufficient to perform an emergency stop when needed since the Superbus drives on rubber tires. The friction between the road surface and a rubber tire is significantly higher than between a rail and an iron wheel of a train. TU Delft project The Superbus project is a joint project of multiple faculties within the Delft University of Technology in the Netherlands, including Aerospace Engineering, Industrial Design Engineering, Electrical Engineering, Mechanical Engineering and Civil Engineering. The project is funded by the Dutch government, the bus company Connexxion and many other sponsors.. The aim of the project team is to have a fully functioning demonstration vehicle ready in due course of 2008.

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6. Design challenges encountered All the four design projects described have several design challenges in common. The one that poses the most problems is the fact that they all start from an original and in essence fairly simple idea and eventually have to reach a state of maturity where full scale demonstration becomes possible. For the projects Ladder mill, Nuna and Superbus it will be discussed how these design challenges are being handled. The project on kite propelled ships is still in the early design phase and will not be discussed further. For the Ladder mill the first mile stone is the practical demonstration of the concept. This proved to require a lot of trial-anderror work. For the Nuna the winning of the World Solar Challenge was the biggest challenge. For the Superbus the ability to show the working of the concept to the outside world within a reasonable amount of time but without getting into unfair competition with other parties in this outside world proves to be the major challenge. Ladder mill The basic idea of the Ladder mill is very simple. Just combine the essential characteristics of a kite and a towed glider in a combined motion and link the cable to a generator. The technology of a kite is fairly old. The Chinese have been flying kite for thousands of years. The technology of a towed glider is at least 100 years old and the technology of an electric generator as well. The main problems encountered so far were in the control of the combination. Controlling kites is an area that is (almost) non-existent in literature. Available literature shows the theoretical basis but practical solutions have not been found in literature. This resulted in a search for possible practical solutions in combination with the existing theoretical basis. Since kites in general are very flexible structures the larger kites are controlled by many wires. The minimum amount of wires use for control of surf kites is four. The control motion of these wires is rather large. This would lead to premature conclusion that the best way to control the kites in the Ladder mill is to use at least four winches, each controlling a separate control wire. However this conflicts with the idea of having only one wire going to the generator. The way in which this problem was solved was to look more into the fundamentals of the control system of the four wires. In essence they control the leading and trailing edge of the sides of the kite. These sides are normally made of flexible textile. The solution found for the problem so far was to make these sides rigid and having a small cart moving along this side. The position of the cart gives a specific combination of a tensile force on the leading and trailing edge of the side. The most forward position would lead to a tensile force on the leading edge only and no force at all on the trailing edge and vice versa. Positions in between give other combinations. 106

The next step in the design process was to really build and test this setup. In the description of the Ladder mill this has been discussed. Here a new design problem was encountered. The problem of making the design in real, making it such that is weighs as little as possible, making it such that it is reliable and finally making it controllable via remote means. This was approached via a series of trial-and-error steps. First designs failed structurally or got damaged. Later designs were made more robust. Control was first achieved by use of standard remote control equipment for radio controlled airplanes. Later this was miniaturized using the development of dedicated printed circuit boards designed for computerized remote control. Similar steps were taken in the development of the ground station. Again the basic idea is simple but the realization took quite some time. The first ground station was built on a simple trailer. It was chosen to make it movable in order to be able to transport it to any location in the country for testing and demonstration. A later development shows a ground station built onto a small truck. Future development will show the use of a larger truck and eventually a fixed base ground station. Nuna The basis idea of the Nuna solar cars is fairly simple as well. Make a vehicle that has solar cells on top and connect them to an electric motor to propel the vehicle. Again the essential technologies needed are not new. The design challenge in this design project is to make the vehicle as fast as possible. This requires an extensive search for the best technology and moreover the combination of them leading to the best performance. In this project the approach taken was to first make a thorough analysis on what would be the factors that would contribute to victory. The majority of them proved to be technical but some of them proved to be nontechnical. Examples of them were the composition of the team and the funding available. Technical aspects were for instance a low vehicle weight, low aerodynamic drag and high efficiency of the solar cells and the engine. They were all treated in combination in order to see interdependency effects. For instance one could decide to buy solar cells with a very high efficiency but thereby spending the whole budget available. Or one could decide use a higher efficiency engine but thereby increasing the vehicle weigh too much. For every major decision these so-called winning factors were used and the decision taken was based on the integrated analysis of them.

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Superbus The basic idea of the Superbus concept is fairly simple as well. Make a road driven vehicle that is fast and sustainable, let it drive on simple light weight infrastructure and use a demand driven logistic system that is highly ICT supported. Again all basic technologies are available. The design challenge is to combine them in one transport concept and show this to the outside world which is rather skeptical and anxiously waiting for results. The design approach taken in the Superbus project is to use the concept of a demonstration vehicle supported with a limited amount of additional research on the other aspects of the transport concept. The demonstration vehicle is definitely not a prototype. It will show the basis elements of the concept and makes it possible for everyone to “touch and feel” it. It will not be made such that it can move into series production but it will merely serve as a test bed. This approach fits with the role a university has to play in society. A (technical) university is funded by society to create new inventions and show what is (technically) possible. It is not the role of university to produce things on a large scale and implement them in society. That role is the role of the general public, the politics and the commercial companies. Developing a test bed is therefore the ideal way for a university to play its role in a clear an fair way. In this way it will never end up in unfair competition with commercial companies. One thing that has to be watched closely in this process is that university does not give away its inventions too soon and too cheap. Using a (semi)commercial outlet of start-up companies might be the right way to protect the interests of universities.

Conclusion In all projects described the commonality is that based on a fairly simple idea it has to come to detailed full scale hardware. This involves a lot of trial and error in case of new things like the Ladder mill. In case of the drive to win a contest an thorough analysis of the winning factors like in the case of the Nuna solar cars can help. In case of larger projects like the Superbus it is very important to have university play its role in a clear and fair way. In this case the development of a demonstrator/test bed is the approach taken. For new project experience gained in these projects will of course be used.

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References [1] ASSET, 2003, ASSET Vision, www.lr.tudelft.nl-asset, TU Delft [2] Breukels, J, Ockels, W.J Past, present and future of kites and energy generation",., PES2007 Clearwater, FL, USA, pp. 1-6 [3] Lansdorp, B., Ockels, W.J., 2005, Design of a 100 MW laddermill for wind energy generation from 5 km altitude,., 7th World Congress on Recovery, Recycling and Re-integration, Beijing, China, pp. 1-6 [4] Lansdorp, B., Williams, P , 2006, The Laddermill - Innovative Wind Energy from High Altitudes in Holland and Australia,., Windpower 2006, Adelaide, Australia, pp. 1-14 [5]

Melkert, J.A., 2006a, Bouwdoos infrastructuur Superbus (Toolbox infrastructure Superbus), [report] Delft: Faculteit Luchtvaart- en Ruimtevaarttechniek, TU Delft

[6] Melkert, J.A., 2006b, Kostenraming van het Zuiderzeelijntracé voor de Superbus (Cost estimate of the Zuiderzee link trajectory for the Superbus), [report] Delft: Faculteit Luchtvaart- en Ruimtevaarttechniek, TU Delft [7] Melkert, J.A., 2006c, Ontwerpverantwoording en Systeembeschrijving Superbus (Design and system description of the Superbus), [report] Delft: Faculteit Luchtvaart- en Ruimtevaarttechniek, TU Delft [8] Melkert, J.A., 2006d, Modellering van de Superbus in het Landelijk Model

Systeem en bepaling van de uitgangspunten voor de exploitatieberekening (Modelling the Superbus in the National Modelling System and starting points for calculating the operational costs), [report] Delft: Faculteit Luchtvaart- en Ruimtevaarttechniek, TU Delft [9] Ockels, W.J., Melkert, J.A., 2004, Dossier Superbus (File Superbus), [report] Delft: Faculteit Luchtvaart- en Ruimtevaarttechniek, TU Delft [10] Ockels, W.J., Lansdorp, B., Breukels, J., Spierenburg, G.J., 2004, Laddermill, work in progress, EWEC 2004, London, UK, pp. 1-7 [11] Ockels, W.J., Ruiterkamp, R., Lansdorp, B, 2006, Ship propulsion by Kites combining energy production by Laddermill principle and direct kite propulsion, Kite Sailing Symposium, Seattle, USA., pp. 1 – 9 [12] Podgaets, A.R., Ockels, W.J., 2007, Laddermill sail - a new concept in sailing" International Conference on Engineering Technology ICET 2007, 11 - 14 December 2007, Kuala Lumpur, Malaysia, pp. 1-14. [13] Verduyckt, T.J., Melkert, J.A., 2006, Bijdragen voor de Strategische Milieube-

oordeling van de Superbus (Contributions for the Strategic Environmental Assessment of the Superbus), [report] Delft: Faculteit Luchtvaart- en Ruimtevaarttechniek, TU Delft

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Delft Science in Design 2 M. Eekhout et al. (Eds.) IOS Press, 2008 © 2008 IOS Press and the authors. All rights reserved.

Innovation-Focused Ship Design Developments and options from a European perspective Hans Hopman

Professor of Ship Design, Delft University of Technology, Faculty of Mechanical, Maritime and Materials Engineering, The Netherlands Abstract The European shipbuilding industry has been able to survive by focusing on building ‘specials’. In order to maintain this position, it is an absolute necessity for the European shipbuilding industry to remain innovative. However, it is difficult to realise product innovations in this industry. The series are usually too small, the development time too short and the risks too high. This article will discuss several developments and some measures that should be taken in order to stimulate the realisation of product innovations. Keywords: Ship Design, innovation, systems of systems, partnerships, goalbased regulation.

1. Introduction At present the shipbuilding industry is flourishing. In spite of the strong position of countries in the Far East, to date European shipbuilding has been able to hold its own. As regards the total volume of ships built per year, in the last few years the European shipbuilding industry, united in the Community of European Shipyards Association (CESA), has been far outstripped by South Korea and Japan; but in terms of the financial value of the ships supplied Europe can still compete with its rivals in the Far East and until 2005 was even number one [1]. This is mainly because European shipbuilding has specialised in building ‘specials’ – complex ships which are custom designed and in which advanced and often new technology is used. These are ships such as dredgers, yachts, cable ships, patrol ships and cruise ships, for which there is little question of mass production. In contrast, shipbuilding in the Far East is mainly focused on building large to very large transport ships such as bulk carriers, oil tankers and container ships, usually of standard types. These ships vary in construction price, depending on the size, from EUR 25 to 100 million whereas the construction price of European ‘specials’ of comparable size is EUR 50 to 300 million.

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However, the shipbuilding industry in the Far East is rapidly catching up as regards technology. The present European position can only be maintained and strengthened by ongoing innovation. Europe owes its present position mainly to its superior knowledge, embedded in a close network of shipyards, suppliers and knowledge centres. In countries outside Europe there is scarcely any network of this kind [2]. Unlike in the car and aircraft industries, prototypes can rarely be used in shipbuilding; the series are too small and the risks too high. Innovation is therefore not a simple matter in shipbuilding, especially in the case of custom-built ships.

Figure 1a: Standard transport ship

Figure 1b: European ‘special’

2. Process innovation versus Product Innovation Only a limited number of product innovations are implemented in shipbuilding because the financial consequences of these innovations would have to be calculated at the initial stage in order to allow for them accurately enough in the quote. In many cases there is not enough time for this. Ships are usually ordered on the basis of conceptual designs which have been created within a few weeks. In shipbuilding the prototype and the end product are frequently identical and there is little scope for introducing radical product innovations. As a rule the margins in shipbuilding are narrow and the risks associated with innovations therefore tend to be too high. Any innovations there are in ship design are more likely to be evolutionary than revolutionary in nature. It is therefore not surprising that in shipbuilding attention is paid mainly to improving the engineering and production processes. In the past these processes were very labour intensive and often of a repetitive character. As a result, investing in improving and automating these processes yielded quicker results for shipyards. The European shipyards which still exist owe their survival mainly to the way they have rationalised and structured their engineering and production processes. The relatively high hourly pay in Europe in comparison with countries such South Korea and China is in fact largely compensated by using fewer workers and smarter production methods.

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However, by specialising in certain types of ships, a shipyard can also increase the repetitive character in the development of the product. By using product experience gained from previous ships it is possible to realise product innovations which can yield quicker results. The fact that this formula can be successful is shown by the number of shipyards in Europe which have acquired a leading position in the market or even become market leaders.

Figure 2: European ‘specials’

3. ‘Systems of Systems’ approach The role of supply companies in shipbuilding is becoming increasingly important. In the past knowledge of both ship design and the design of systems to be placed on board was to a large extent available at the shipyard. The materials, components and sub-systems needed to build the ship were then ordered from the appropriate suppliers (see Figure 3a).

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Fig. 3a. Shipyard buying sub-systems & components (old situation)

During recent years there has been a clear trend in shipbuilding towards shipyards hiving off more and more areas of knowledge to supply companies. This is a logical consequence of the fact that the knowledge needed to design and build complex, innovative ships has become more and more varied, so that the number of areas of specialist knowledge involved in these processes has grown rapidly in recent years. Many companies with specialist knowledge they do not need directly for their own core activities have placed this knowledge outside the company because it is more efficient to concentrate this capacity in new specialised companies. On the other hand there is also a trend whereby system-related companies are entering into new forms of collaboration in order to gain a stronger market position together. In this way a large number of groups of companies have emerged which are able to take on the responsibility of supplying complete ship systems (See Figure 3b).

Fig. 3b. Shipyard buying systems & components (present situation)

Examples of this are companies such as Wärtsilä and Rolls Royce which are now able to supply complete propulsion and manoeuvring systems to the shipyard as a turn-key system. As a result, not only the scope of delivery, which was previously limited to supplying only diesel engines or gas turbines, has risen considerably, but also the responsibility. By taking on the responsibility of supplying the intake and exhaust systems, propellers, rudders and the integrated operating and monitoring systems as well, these companies also make themselves responsible for the integration of these sub-systems into the whole system. The main systems such

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as the integrated generation and distribution of electrical energy on board ships, accommodation and the concomitant ‘hotel systems’ are now often delivered by one supplier. This system-bound grouping of companies enables the companies to combine their developmental capacities and to harmonise and standardise their products beforehand, thus reducing integration risks. Because they also take over part of the integration and project management tasks from the shipyards, these groups have the strength and power to be attractive, innovative and robust partners. Not surprisingly, it is becoming more and more common for groups like this to initiate developments of their own towards new, integrated solutions for application on board ships (see Figure 4). This means that as regards developments and innovations in the area of materials, components and sub-systems the shipyards have become more and more dependent on supply companies. On the other hand it also means that shipyards can focus more on the important role of ship integrator and on the project and process management that goes with it.

Fig. 4. Design study by Wärtsilä Corporation [3] for an LNG propulsion plant for application on board a cruise ferry.

Another important development is that to an increasing extent shipyards are focusing on the customer. Because the shipyards are becoming more and more dependent on supply companies for new technology their own product innovation will be driven mainly by clever combination and integration of new technologies. Knowledge of operational processes is of crucial importance in creating better designs. Regarding ships as part of an overarching process or system (systems or systems approach) broadens the scope for finding innovative solutions and reduces the chance of sub-optimisation. This approach also makes it easier to design on the basis of life-cycle approximations.

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In the case of transport ships, first considering the entire logistic transport chain opens up a creative scope which facilitates the generation of more effective solutions. Recent examples of this – though developed in the framework of a European project – are the IPSI concept [4] and the recently launched Project CREATE3S. In both cases the innovation has to do with improving the competitive position of European short sea shipping by reducing the conventional loading and unloading times of 8 to 12 hours or longer entailed in loading and unloading container ships with cranes to less than 2 hours. The key element in CREATE3S is to be able to develop a cargo-carrying platform that can be loaded onto or unloaded from the ship in one move. This approach will also improve the possibilities of gearing the vessels to specific trades and help to develop a standard hydrodynamic platform that can be optimised for industrial mass production.

Fig. 5. Conceptual impression of a solution for a new shipping concept based on large cargo modules to be loaded / unloaded in one move.

4. Partnerships Nowadays the only way to realise complex projects is to set up collaborative groups which enter into agreements on the basis of equality and shared responsibility. In this way risks are reduced to an acceptable level for all parties involved and the foundation is laid to work in a joint win-win situation. It is therefore interesting to observe that larger-scale innovations in shipbuilding have nearly all come about through close collaboration between shipowners and shipyards, often supplemented by contributions from supply companies and knowledge centres. The risks entailed in developing new products may be high; but the same is true of interdependence with respect to knowledge. ‘Launch customers’ are essential if innovations are to be applied successfully. It is not surprising that collaborative ventures and partnerships are common in the development of naval ships and ships for offshore operations. What these ships have in common is that their designs, unlike those of

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transport ships, are strongly dominated by systems which must be placed on board in combination with the operational management needed for them. What collaboration between industry and a knowledge centre can lead to is best illustrated by the success of the ‘enlarged ship concept’ (see Figure 6) and the ‘axe bow’ which was a further development of this concept [5].

Fig. 6. Enlarged Ship concept (left) and Axe Bow (right) (by Damen Shipyards)

5. Construction standards The International Maritime Organisation (IMO) is responsible for the development of safety standards for constructing and operating ships. The enforcement of these standards, however, is the responsibility of the national authorities. The standards are usually formulated as prescriptive regulations which are often a distillation of past experience and as such tend to become less and less relevant over time. They are also often unable to cope with a wide range of design solutions and, at worst, may create unnecessary dangers. At the time they were written prescriptive regulations encoded best engineering practices, but with evolving technologies they may rapidly become inadequate. In fact, it is quite probable that in the long run prescriptive regulations prevent industry from adopting current best practices or – even worse – safer solutions. To discharge their legal responsibilities designers applying such regulations are only required to carry out the mandated actions. If these actions prove to be insufficient to prevent a subsequent accident, at present it is the regulations and those that set them that are seen to be deficient, not the designer applying them, even though in law it is actually the designer’s responsibility. In May 2004 it was agreed that an IMO Maritime Safety Committee (MSC) should start to develop a so-called ‘goal-based’ approach. Goal-based regulation does not specify the means of achieving compliance but sets goals that allow alternative ways of achieving compliance. Such an approach gives greater freedom in developing technical solutions and ac-

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commodating different standards under the assumption that it is the innovator who is best placed to ensure the safety of their design, not the regulator. This development will make designers more aware of the risks they introduce in their designs as a result of decisions made during the design process. More important, however, is that the use of goal-based standards not only supports innovation but should also result in safer solutions. For defining criteria the MSC is considering the use of a probabilistic riskbased methodology based on the ALARP (As Low As Reasonably Practicable) principle. This methodology divides risks into three categories: unacceptable, tolerable and negligible (or broadly acceptable). For the tolerable risk category the ALARP principle is to compare the cost of further risk reduction with the costs which would be incurred in the event of an accident. This means that when the cost per life saved by a further risk reduction within the tolerable region exceeds the assigned value, the implementation of this extra reduction measure will not be required. An example of an ALARP diagram is given in Figure 7.

Fig. 7. Example of an LPG carrier’s risk matrix for collisions at sea

Although some first steps have been taken such as agreement as to basic principles and goals, there is still a long way to go in order to arrive at consensus on goal-based standards for new ship construction.

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Another development related to standards is the need for safer and more environmentally friendly ships. New legislation is coming into force that will stimulate investment in better and safer ships. This need for so-called ‘quality shipping’ will also entail the development of new technologies and innovations.

6. Process for the creation of systems The designing process in shipbuilding is a creative and complex process and is an important part of the whole production process (see Figure 8).

Fig. 8. Generic model for the creation of systems

Contracts for the construction of new ships are usually entered into on the basis of conceptual designs which have been developed within a very short space of time, in most cases a few weeks. As Figure 8 shows, after the conceptual design has been completed there are many further stages before the physical product can actually be tested with regard to its required performance. However, risks can be minimised for instance by using familiar and proved production methods, components and subsystems. In addition, calculation models are often used to predict the performance of the product as accurately as possible in advance. In Figure 9 the ‘left part’ of the production process as shown in Figure 8 is shown in more detail and two parallel development paths are distinguished: • the development of the operational architecture (the requirement package), and • the development of the physical architecture (the solution).

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Fig. 9. Generic design process based on a ‘systems of systems’ approach

Figure 9 also shows the processes which take place before the conceptual design is generated. These processes entail the design of the best operational concept on the basis of which the requirements can then be drawn up for the ship needed. The importance of this stage is being recognised to an increasing extent, since it is not only important for the ship to achieve the desired performance but also for the ship to realise or support its user’s operational objectives in this performance. In most cases not all steps of the process have to be traversed for every aspect of a new ship design. If optimal use is made of standard requirements (SOLAS, classification bureaus etc.) and suitable off-the-shelf solutions for the materials, components, sub-systems etc., the process can be very much simplified. The innovative part of the design process is usually focused on generating concept and system designs and on the quality and safety standards which must be met. However, if new technology is going to be introduced in the ship design, the design will have to be worked out at a corresponding level of detail. To be able to take this information into account in preparing a quote requires greater detail in the design in the pre-contract phase. However, modern software in combination with increasingly powerful computers now make it possible to include more and more design details and variations in the initial plan.

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7. Computer tools In the design process analysis or simulation tools are often used to show how the design’s performance measures up to the requirements. In the initial phase analysis tools are usually based on regression analyses of previously constructed designs. This means that these tools lose their validity as the information on which the analysis is based ages or if the new design is too different. As a rule these tools are not suitable for analysing product innovations. However, with the help of analysis tools based on ‘first principles’ it is now becoming easier to analyse the feasibility and consequences of new, different solutions for both the product and the process. For example, it is now possible to determine a ship’s resistance on the basis of a ‘first principles’ tool (see Figure 10).

Fig. 10. Result of a CFD-calculation for a new ship design (RAPID–MARIN)

First principle tools usually require a more detailed description of the design and in the conceptual phase this information is not always available or there is not enough time to generate it. This has often led to opportunities for innovation being lost. However, new CAD tools and more powerful computers are now making it easier and easier to obtain more detailed design information in the initial phase of the design, to generate several alternatives and therefore to arrive at better designs. An example of a recent CAD tool still under development at Delft University of Technology [6] is a genetic optimisation algorithm for space allocation in the conceptual design phase of naval ships. Some preliminary 2-D results of this tool are shown in Figure 11.

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Another possibility is to make a division at the various levels of detail in the design between the topological description and the geometric description, as shown in Figure 9. The topological description refers to the structure of the design while the geometric description defines the dimensions that go with it. In principle the structure is determined by the designer and this work is creative in nature; the optimal dimensions to go with the particular structure are calculated by the computer.

Fig. 11. Computer-generated arrangements for an Offshore Patrol Vessel using a genetic optimisation algorithm.

This approach enables designers to make alterations in the dimensions even at quite a late stage of the design process with minimal consequences for the completion time of that process. This makes it easier to apply concurrent engineering. It is also possible to copy the detailed topology of detail solutions used in previous designs in the description of the new design. In this way the details of a design can be realised more quickly.

9. Systems Engineering The increasing complexity of man-made systems has led to new opportunities, but also to growing challenges for the organisations that create and utilise these systems. There is therefore a need for a common framework to improve communication and cooperation among parties which create, utilise and manage modern systems so that they can work in an integrated, coherent fashion. An example of such a framework is Systems Engineering, a common process framework which covers the whole life-cycle of man-made systems. Several standards [7] have been developed based on the process framework as shown in figure 12. This representation of the process framework is also known as the V diagram and has some features in common with the diagrams shown in Figures 8 and 9.

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Fig. 12. The Systems Engineering process framework

At present very little use is made of Systems Engineering in shipbuilding. One approach might be to limit its introduction to just a few processes.

10. Conclusion Europe owes its present market position largely to its superior knowledge, embedded in a close network of shipyards, suppliers and knowledge centres. The present European position can only be maintained and strengthened by ongoing innovation. Innovations which lead to more effective and more efficient engineering and production processes can yield results more quickly because of their repetitive character. It is not so easy to realise product innovations in the European shipbuilding industry, because the series are too small, the development times too short and the risks too high. Nevertheless, there are certain developments which may stimulate product innovations in European shipbuilding or certain measures may be taken to that end. The following measures and developments may play an important role: • specialisation in certain types of ships • forming collaborative groups or partnerships with supply companies and knowledge centres • focusing more on the customer’s processes • the development of goal-based standards • the promotion of safer and more environmentally friendly ships • the development of first principles analysis tools and new design methods.

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Provided it is applied selectively, an additional option is Systems Engineering, which is specifically intended for the realisation of complex systems of a multidisciplinary character. Finally, of course other, more political factors also play a role in strengthening the position of European shipbuilding. For example, an important precondition if shipbuilding is to remain attractive to entrepreneurs is the creation of a level playing field.

References [1] CESA Annual report 2005 – 2006, 2006-09-12. [2] LeaderSHIP 2015, report of the High Level Advisory Group, 2003-10-30 [3] S. Hannula, ‘LNG Cruise Ferry – a truly environmentally sound ship’, document, www.wartsila.com [4] J.A. Ottjes, H.P.M. Veeke,´Simulation of a new port-ship interface concept for intermodal transport´, Proceedings of the 11th European Simulation Symposium (ESS 1999). [5] J.L. Gelling, ‘The Axe Bow: The Shape of Ships to Come’, 19th HISWA Symposium on Yacht Design and Yacht Construction, 13 and 14 November 2006, Amsterdam. [6] B. van Oers, D. Staperma, H. Hopman, ‘Development and Implementation of an Optimisation-Based Space Allocation Routine for the Generation of Feasible Concept Designs’, COMPIT 2007, April 2007. [7] ISO/IEC 15288, ‘Systems Engineering – System life cycle processes’, first edition 2002-11-01. [8] W.J. van Griethuysen, ‘Marine Design – Can Systems Engineering Cope?’, IMDC 2000, Korea, May 2000.

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Integrated Design Integrated Design in Architecture - and what comes next? Ulrich Knaack1

1 Professor for Design of Construction, Faculty of Architecture / TU Delft, Netherlands Abstract This article describes the basic demands on architectural design such as function, aesthetic and technology with a focus on how to integrate the different disciples in the design process. One solution is the “integrated design” where the design team develops the design in collaboration and comes to mutual conclusions. This method is described on the basis of two projects where the author was responsible for the design and the planning process. Lastly this paper discusses a vision for future developments of the design process with a focus on value orientated results.

1. Introduction A personal statement to start with: my interest in architecture derives from its combination of aesthetic form, functional aspect and technical solution: the task at hand is always to design a building within an architectural content, with a specific organization and function, at expected costs and for certain technical demands. Here we have to make decisions for or against formal aspects and technical solutions. Sometimes the technological method provides the starting point for a design idea, which ends in a formal discussion about positioning and relations of structural and enveloping components. In other situations the formal idea leads to constructional solutions for the structure – like skeleton or massive constructions depending on the expected appearance. Finally the functionality and its organization within the building will control the design. These aspects make designing architecture a challenge – the engineer in the architect sees right or wrong and wants to come to a technically correct solution; the artist within however searches for the final and perfect combination of elements and formats. In the end the entire unit has to work as an organism, in which people can live or work and last, but not least, feel comfortable. This leads to the point that different architects come to different solutions for the same project – and the tradition of project competitions is therefore very exiting: to find the best possible solution for a given situation, reflecting all above mentioned aspects by dif-

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ferent architects and design teams with their various starting points and influences. In addition to the personal and historically positioned formal objectives, trends and fashions in architecture there are some basic developments worth mentioning: architects are well trained in integrating new technology in their design work. New materials and technical solutions are always welcome – even if the building has to be built as a 1:1 model in order to prove the theory. Secondly, today’s buildings’ energy demands have led to the development of energy standards – in principle a well intended and needed request. However, the issue lies in improving promised results and the interaction with the user – not everyone needs a formula 1 car for traveling. The question in this case is how to fulfill energy saving demands in an understandable, practical and technically sensible manner. Finally the line of communication between client, user and planner is an aspect of interest. The traditional process of creating architecture was orientated on a limited amount of technical solutions and required only the collaboration of a small group of consultants. Current architectural design requires comprehensive integration of all technical and functional demands reflecting the formal aspects starting right in the planning process. The architect is therefore trained to communicate with consultants such as structural engineers, climate designers, building physicians, facade planners, cost consultants, logistic and facility management planners – just to mention a few of the disciplines involved. Considering the growing number of new technologies available in the industry and increasing overall demands the architect is challenged to keep on top of this knowledge, isolate sensible solutions and integrate them in the design concept. In the subsequent design process the concept needs to be developed from the initial planning draft into an executable building. The last step of the design process is the control of the building process itself: here the architect and the design team have to guide the construction on site and find solutions for issues not previously defined and any problems occurring during the actual execution. This process of so called “integrated design” requires a technical and formal education as well as the capability of abstraction and reflection, overview, interest in detail solution and communication. In terms of the appearance of a building; the described planning process includes the development of a basic aesthetic idea with general suggestions for technical solutions, which the architect then gives to the general contractor. The planning process is concluded by the contractor deciding on the final structure, construction and quality of materials – a process, which might provide a cheaper building but can not guarantee the best solution – the differences in objectives between the client and the con-

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tractor are just too big. As an alternative the architect could accept more responsibility by acting as the general planner in the process. This would mean to include all the other planning disciplines into his contractual responsibilities. The architecture would therefore have to integrate as well as control all aspects of the planning disciplines involved. Besides the risk for and the additional demands on the architect, the overall positive aspect would be that the control and decision making of the entire project would lie in the hands of the architect providing a better inclusion of his design concept. And the design of the process is also part of the design – virtual in terms of the relationship between the parties involved, and real in terms of the built result. Controlling the flow of money in a project means controlling the final result and its quality (1, 2, 3).

Figure 1 – Classic design process: the main drivers of the process are the client and the contractor. Planning parties provide information and determine quality standards. The conflict is direct and predestined. Quality has to be controlled both by the client and the planning partners.

Figure 2 – Design process with general planning: the main drivers of the system are the client, the contractor and the general planer, who combines the planning parties. This shift in the system gives the planning parties power to control parts of the process.

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Figure 3 – Design and building process: the main drivers are the client and the contractor, who uses the planning disciplines to provide information. Quality is controlled be the contractors. The conflicts in this scenario are also direct. Loss of quality control can result, depending on the positioning disadvantage of the process.

2. Two Projects – Debitel / Stuttgart and König Arena / Krefeld The following two examples are given to explain the possibilities of integrated design process and general planning under consideration of the building objective, the strategies for the planning process and the final architectural results. Both projects were executed with the architectural company RKW – Architektur und Städtebau / Düsseldorf where the author owned responsibility for a profit centre. Both projects were executed as “fast track projects” with an extremely limited time schedule.

Figure 4 - Bird’s eye view of the development Debitel headquarters

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Debitel headquarters in Stuttgart For the German mobile phone company Debitel this 40,000 m² headquarters facility was developed on an existing business park location. The initial objective was to find a functional organization for a growing company providing easy communication and interactivity between the different departments. The design translation of these goals was a series of connecting elements between the office units. Secondly the company needed some manner of identification to express its position within the city and the market. To address this issue a part of the building was developed as a high-rise in the centre of the business park.

Figure 5 – Concept of ventilation and facades in different climate situations for the high-rise part of the building complex debitel. (Picture by Transsolar / Stuttgart)

By integrating disciplines such as climate designs and structural engineering right from the beginning of the project, the architects designed the project in an interdisciplinary team. One example of this interaction is the “solar chimney” in front of the high-rise part of the complex:

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The architect wanted to include natural ventilation in the project. To address this request the climate designer developed a “solar chimney”, described its function and suggested the position within the building. Following a team discussion he suggested its integration into the façade: By positioning the chimney on the outside of the building, not only do the pressure differences in the chimney generate air transport in the system; but the thermal impulse also implements pressure differences - a principle, which was not used for such purposes before. With the described pressure in the system, the solar chimney provides natural ventilation of the building by exhausting the offices spaces (4).

Figure 6 – Solar chimney as part of the façade

At this point the architect again got involved, worked on the aesthetic design of this new solution and developed the chimney into a formal object giving the geometric body of the high-rise building an aesthetic shape. The conclusion was to not only expose the chimney but also the stairs and elevators – with the result that the body of the high-rise was divided into segments. This changed the visual impression to emphasize the building’s vertical orientation. The chimney was placed – in correct orien-

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tation to the sun – centered on the main entrance of the building. So in its technical function it acts as the driving force of the mechanical ventilation and in its form-giving function as an exclamation mark for the entrance and the building in its urban surroundings.

Figure 7 – Main entrance and solar chimney of the high-rise part of the building complex debitel

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The design of the twin-face façade underwent a similar development. Current technology divides between four different principles of twin-face facades: boxed windows, adding a signal glazed window in front of an inner window; a second skin façade where the extra layer of glass covers the entire façade; corridor facades with a glazed corridor with vertical slots in front of the inner facade; and finally the integration of a story-spanning chimney in the façade cavity.

Figure 8 – Boxed Window

Figure 10 – Corridor façade

Figure 9 - Second skin façade

Figure 11 – Chimney façade

For the Debitel project the design team of architects and climate designers chose a combination of standard facades with fixed sun screens and boxed windows – a system, especially developed for this project and later

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used in various versions as a so called “hybrid façade”. This system was developed to provide the user with the options of controlled natural ventilation and personal access to the outside air, if required. But at the same time, the advantages of twin-face facades were to be maintained: control for sun protection during high wind situations with an inner sunscreen and sound protection. This part of the design process was executed in the way previously described: combining ideas and knowledge within the team without distrust or one-sided control. The result provides the requirements for maximal protection of twin-face facades and combines them with the simplicity of single layered facades and the possibilities of individual control (5)

Figure 12 –Principle of the hybrid façade

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Figure 13 – Detail solution of the hybrid façade: developed as an element façade, serpentine and prefabricated elements are suspended from the floor/ceiling slab.

Figure 14 – Final hybrid façade with twin faces façade parts with integrated movable sunscreen and individual operable windows behind the fixed sunscreens

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Figure 15 – Construction side of the hybrid façade

All this takes place right at the beginning of the project – when the client still needs to be convinced. This means that emotional/sensual aspects of the design will have to be positioned and explained; construction and its functionality to be improved upon and costs to be guaranteed. During this initial period of the project the design team might not yet be in its final configuration; additional members might be needed and others reap-

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pointed or exchanged. Such changes might influence the later design, impacting all other aspects. But it is also the time during which the quality of the team becomes apparent – can it handle the ideas, the technology and the appearance? And the cost? My solution for this period of the project and for guaranteeing aesthetic quality for the remaining design and building process is to implement “general planning”. General planning means that the architect as leader of the integral design team takes on the responsibilities for the entire team and transports the final design including all aspects. With this strategy he will guide the team members, control the solutions being presented and the money flow within the project. Especially this last aspect - money flow – is important: even though it seems counterproductive to the aesthetic design finding process, it is one of the most important topics to control architectural quality. König Arena Krefeld The second project to be described is the ice stadium in Krefeld. It is a stadium with standard use for ice hockey and the optional use as a stage, either centric or eccentric. About 8,000 seats and 20 VIP lounges with a business club are available. In the process the client was requiring an architectural design and a contractor proposal as an integrated solution – a “design and build” project. This means that besides the architect and the consultancies the contractor himself participates in the design process. The final design’s goal was to express the purpose of the stadium as a place for ice hockey as the main objective and concerts as a secondary use. The facade was therefore designed as a glass layer, with different lighting expressing the current use: blue for ice and amber for concerts. In addition the façade had to be kept within tight cost limits since competitors were developing without a façade and therefore entirely without façade related cost. You can imagine the discussions taking place due to inherent conflicts of interest within the design team willing to win the race.

Figure 16 - Interior during construction process

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Figure 17 Bird’s eye view of the ice stadium / Krefeld during building process.

An additional issue worth mentioning was the solution for the climate design. When developing office buildings we have to improve the quality of cooling and natural ventilation due to an already good insulation of our current facades. When designing housing we have to insure the quality of insulation and try to keep as much energy as possible within the building. The demands for a stadium are entirely different since this building type is being used only short periods at a time with a huge demand on ventilation during these periods. Consequently the ventilation system is the main instrument to control climate in the building and we need to focus on several mechanical ventilation units that condition the building simultaneously. For the architectural design this means building without massive structural constructions and without trying to integrate natural ventilation – obviously, this influences the design. To conclude this part I would like to emphasize that designing and building architecture is always related to the personal relationships between the participants: the members of the design team have to accept and understand each other. And even though most members are educated to do so this requirement remains a critical point in the process, specifically when financial aspects are involved. Then the relationship with the con-

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tractor and builders has to improve since final decisions are made when these parties are involved, and the design idea is finally executed on site. And lastly the client has to be impressed by the building because he will be the one using the building and paying for it. The conclusion is that – in addition to an aesthetic, functional and technologically sound idea – the communication and working process such as “integrated design” is an important aspect of architectural quality.

Figure 18 - 19 - Main façade of the ice stadium with the alternative illumination scenarios to generate branding for different uses – ice hockey games or concerts. The change of the colors of the lightning expresses the different uses: ice blue for hokey to amber for concerts.

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3. Value as an orientation and task for design process Even when the described process is an “integrated design” it might not really integrate all possible aspects. The next question is how to develop future strategies for the design process. “Integrated design” focuses on the demands of the building and the user and tries to develop design solutions for both. We can divide this into two basic demand qualities: the direct need to improve minimal features of the building such as heating or natural daylight, and the indirect need. This would include enrichment of the building features by adding extras like cooling during summer time or a natural light system to control reflections etc.. The task for the integral design process is to find and improve upon such aspects and provide solutions in the design proposal.

Figure 20 - Guggenheim Museum by Frank O. Gerry in Bilbao

Now focusing on the next step of development within the design process we have to find solutions for unexpected demands. This could include the possibilities of a re-use of the building to increase its live span, or – even more interesting for the decision making process – potential added value that can be generated by the building. This can be achieved by focusing on the building’s branding and possible interaction between the architectural object and its positioning within the city and the market. Projects 139

like the Guggenheim Museum in Bilbao, a city in Northern Spain previously not well known throughout Europe, can explain this so-called “Bilbao effect”: Architecture can be used as an instrument for positioning and can generate added value. But the added value that, for example, the Guggenheim Museum generates for the city of Bilbao, can not be directly aligned with the building costs – how should this be evaluated, even if it is measurable? For the design team the conclusion of this reflection is that this added value will have a positive influence on the project and therefore needs to be part of the considerations during the design process. Finally added value can be just as much a benefit for the client and the user; improved quality - even at higher cost - results in more than just the sum of all elements (6). To extend on the above mentioned aspects and to develop ideas for the next steps it seems reasonable to ask what additional values will be expected in the future. Here begins the interesting part of the assumption: do we expect more comfort or more space? Will individualization and personalization be a future requirement or are we going to focus on the quality of space and design? Besides the more marketing related aspects of “fashions and interests”, the most important driving force for future building development will be energy: its accessibility, production and consumption. The reasons are obvious; but the important question is in how far the building structure and architectural design need to be geared to this development. Secondly, ecology will gain even bigger importance than it has today. Architecture already deals with climate as a design tool and an ecological and energetic concept for the design proposal is becoming a standard. But aspects such as the energy used to produce constructional materials or the disassembly possibilities of buildings need to be further investigated and implemented into the design process. Finally, efficiency will be another important topic for the planning process to give the design a livelong attractiveness - not only related to limitations of energy consumption or financial savings; but rather as a concept for efficient design solutions in terms of organization, synergies between functions and capacity for individuality . But if we define the topics energy, ecology and efficiency as key items for demands of design, how can we apply values to them? Energy savings alone with better insulations or new and more efficient technical units can be called solutions for some demands. The added value could lie in the option of reusing buildings with different, not yet known functions: today a building’s useful lifespan is considered to be a minimum of 20 years; but this could be extended to 100 years or more. Here we would add a value, which is not noticeable at present but guarantees a benefit for society and the client. Secondly, the reuse of existing buildings is a topic to consider:

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60% of future building budgets are going to be used in the field of refurbishment and renovation, only the remaining 40% will be invested in new constructions. These numbers show that there is a need to focus on this topic and to find solutions for existing buildings as well as the redesign for current or even future expected uses (7) Of course architects are always interested in new technologies – here they can find new topics to draw attention to their designs and new influences to give impulses for certain developments. At the same time the building industry is conservative in principle. The reasons are that on the one hand established methods of constructions exist that builders and users are used to and feel comfortable with. On the other hand the building itself has to stay and function for a certain period of time and is mostly an individual development – which means that the possibilities of serial production and copying are limited compared to other industrial products. Still, there is a trend in architecture of using new materials and the application for materials to be used in constructions. We can define two directions – a structural use, which requires knowledge and material improvement and its application in the building. This is an inherently slow process. The alternative option, which is well established and executed, is the use of newly developed materials for the interior – without any risks and only fire safety concerns – or for facades, where a certain risk of failure is acceptable due to their accessibility and the limited risk for the entire building. Again, the approaches described above serve specific demands; and again we have the opportunity to find added value for the project and society to give an impulse. The difficulty is that we have to develop results for demands not even known yet or to define values from unexpected viewpoints and tasks. A fundamental solution to this problem requires a system, which will accept changing demands and can adapt to influences for alternative solutions. To cerate such a system we have to think in completely open structures and to try to develop elements and connections. The structure itself can only be a schematic of collaboration and linking, not a physical construction. Secondly, the elements have to be developed on an existing technology base to be integrated and usable right now. Finally, in order to create a solution that is adaptable for any future integration, the individual elements need to be connectable. It has to be an open system – we all know this technology from network systems or, for example WIKIPEDIA, where anybody can insert his information and the public has simultaneous access. The question is how this can be achieved for architecture.

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4. Conclusion Considering this approach the strategy for developing architectural design has to be an open minded collaboration between the involved parties – concept developers, planners, builders, users and clients – led by an architect who understands and respects the partners. This will be the only way to reach the goal of an emotionally impressive and technically sound object to be used for specific functions: the architectural building. The Netherlands can look back on a long tradition in this regard – architecture is respected as an important part of society and the number of internationally known and very well respected architects is enormous for such a small country. But at the same time fear exists that limited technological knowledge combined with a narrowed focus on only the aesthetic design aspects will guide architecture to be solely responsible for the creative emotional aspect and other disciplines for the actual realization. The result will be a situation as it is developing in Sweden, where the leading role in the design process was taken from architects and placed with the contractors – with the result of decreasing building quality. It is interesting to see that now, after 20 years of this development the clients – and not the architects - are asking for well integrated and technically oriented architects to be the person responsible in the process and are taking action in educational programs for this redevelopment – certainly not for social reasons but with an positive impulse for society in mind.

References [1] Reinhard Seeling: Projektsteuerung im Bauwesen – 1996 Stuttgart [2] Claus Steinle, Heike Bruch, Dieter Lawa: Projekt Mangement – 2001 Frankfurt [3] Ulrich Knaack: Leistungsphase + / Alternativen für Architekten – mit Generalplanung Qualität sichern in Baumeister 5 / 2004 [4] Ulrich Knaack, Lars Klatte, Thomas Auer: „Kommunikation ist alles – die Hauptverwaltung der debitel / Step 6“ in Intelligente Architektur 11/02 [5] Ulrich Knaack, Till Klein, Marcel Bilow, Thomas Auer: Principles of Construction – facades / Birkhäuser 2007 [6] Coosje Van Bruggen: Frank O. Gehry – Guggenheim Museum Bilbao – 2002 New York [7] Thiemo Ebbert, Ulrich Knaack: Principles for facade-renovation of office buildings. Glass performance days 2007, Tampere

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Delft Science in Design 2 M. Eekhout et al. (Eds.) IOS Press, 2008 © 2008 IOS Press and the authors. All rights reserved.

Offshore Structures: Hidden Treasures for Designers Arie Romeijn1, Jan Meek2 1

Associate Professor Steel Structures, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands 2 Offshore Engineering, Delft University of Technology, Delft, The Netherlands Abstract Structures for the production of oil and gas placed in relatively shallow offshore waters are generally fixed structures which are piled to the seafloor. With increasing water depths these structures tend to become more sensitive to dynamic response and fatigue. When entering water depths exceeding approximately 300 meters these conventional fixed platforms are generally not capable to cope with the offshore environment and being replaced by floating platforms. As under certain functional design considerations bottom founded platforms may be preferred over floating platforms the industry developed the so called ‘compliant tower’: a bottom founded platform capable of carrying topside loads up to 30,000 t in water depths ranging from 300 meters to approximately 500 meters. This paper describes the basics of conventional bottom founded fixed platform design followed by the fascinating design and installation aspects of compliant towers and will conclude with the challenging statement that, contrary to the belief of many in the industry, under certain conditions conventional fixed bottom founded platforms may be feasible in water depths up 400m. Key words Offshore, Oil – and gas production, Offshore Engineering, Fixed Platforms, Compliant Towers, Fixed deep water platforms, Fatigue.

1. Introduction When the production of oil and gas moved offshore starting in the Gulf of Mexico the first platforms were designed for and installed in very shallow waters of a few meters. Gradually oil and gas fields were found and exploited in deeper waters resulting in more advanced designs of the platforms which were generally fixed to the seabed using driven hollow tubular piles. With increasing water depths the wave loading and resulting overturning moments on the platforms increased significantly leading the designers to focus on platform designs which, apart from the required strength and stability considerations, were specifically aimed at being as transparent as possible to reduce the wave excitation as much as possible. As a rule of thumb it can be assumed that of the total maximum hori-

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zontal design load on such a platform the contribution of the wind load is only approximately 15%, the remainder of the horizontal design load being caused by wave and current. Moving to more hostile environments, like the North sea, not only caused the design criteria to become more severe, also the transportation and offshore installation of the composing parts of these offshore facilities became increasingly difficult whereas simultaneously the industry aimed at reducing the amount of man hours to be spent offshore. The latter clearly for safety, efficiency and planning reasons. That is why the accepted way of designing, fabricating, transporting and installation of these facilities is generally by using a small number of large and heavy components, as complete as possible, requiring a minimum amount of work offshore. Generally the stiffness of the bottom founded Fixed Platforms in water depths up to approximately 150 meters is such that dynamic response and associated fatigue are not decisive for the platform substructure design. The supporting structures are generally designed for the extreme environmental condition, a combination of maximum wave, wind and current. Typical designs and the associated fabrication, transportation and installation aspects are being addressed in the first part of this paper. Subsequently the problems associated with the moving of the bottom founded Fixed Platforms into deeper waters are being addressed and how the industry came up with a solution to cope with the dynamic response problem. The emergence of the so called “Compliant Tower”, also bottom founded using steel piles. The design methodology will be highlighted and a recent application in a water depth of approximately 400 meters will be used to illustrate the resulting structural dimensions and method of installation. The paper will be concluded by presenting the results of a study revealing that a conventional bottom founded Fixed Platform may after all be competitive for the same design conditions as used for the Compliant Tower as described.

2. Bottom founded Fixed Platforms in relatively shallow water In a typical example of a bottom founded Fixed Platform (fig. 1) the three main elements are the topsides accommodating all the required functions of the platform, the supporting structure or jacket and the piled foundation. The functions and size of the topsides are determined by the size and characteristics of the oil and / or gas reservoir which may be located up to a few kilometers below the sea bed. Generally the wells to produce the oil

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and gas are already being drilled during the period of designing and fabricating of the facilities that will be used for the eventual production.

Fig. 1. Production facilities on a bottom founded fixed platform.

The substructure, or jacket in the industry terminology, provides the necessary strength and stability for the platform to operate safely during its lifetime, generally ranging from 20 to 40 years. It is obvious that certainly for increasing water depths the designer has a clear incentive to make the structure as transparent as possible to minimize the magnitude of the acting wave load and the resulting overturning moment (fig. 2).

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Fig. 2. Main dimensions, masses and wave load for a typical bottom founded Platform.

The shear is predominantly being transferred via the braces whereas the overturning moment is to a great extent determining the required dimensions of the jacket legs. To efficiently support the topside structure and to minimize wave loading which is most severe close to the water surface the aim is to minimize the width of the jacket at the top. Making the base of the jacket wider clearly will reduce the pile loads and the required pile size and or pile penetration. The dimensions of the jacket components are determined by the permanent weight of the structure and very important the maximum design wave applicable in the area of application. For the structure as shown in fig 1, the maximum design wave amounted to approximately 36 meters, also determining the elevation of the bottom of the deck at a certain height above the still water level. For initial design purposes the first natural period of the structure can easily be assessed by some simple modeling (fig. 3). For relatively shallow water platforms the first natural period is generally less than 3 seconds.

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Modeling of fixed structure as a one mass spring system

L = M=

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45 0.05

MN [ −]

3EI 90 ⋅106 MNm 2 = = 90MN / m L3 1⋅106 m3 Fˆ 45MN = 0.5m xS = = k 90 MN / m k ωn = (if μ = 0) → ω n = 2.12 rad / s → Tn = 2.96 s M k=

Fig. 3. Simple model of fixed structure to calculate first natural period.

The loading is therefore considered to be quasi static and the members and joints of the structure have to be checked for all relevant load combinations and various positions of the wave when passing through the structure. More rigorous dynamic response and fatigue analysis is only required when the first natural period is getting too close to the peak of the wave spectrum. This may be the case in water depths nearing some 150 meters in combination with high topside loads and a hostile environment. For reasons as explained the prefabrication of this type of offshore facilities is such that as large and complete sections as possible will be brought offshore. For the platform design as shown (fig. 1) the composing elements are the integral substructure (fig. 4), the piles to fix the structure to the seabed using a hydraulic underwater hammer (fig. 5) and the topsides facilities. The production facility is composed of a huge deck section (fig. 6) only to be complemented by a drilling and an accommodation module to complete the topsides.

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Fig. 4. Prefabricated integral substructure of fixed bottom founded platform.

Fig. 5. Pile installation using hydraulic underwater hammer.

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Fig. 6 Installation of prefabricated integral topside facilities.

It goes without saying that the load-out, transportation and installation of these huge structures have to be engineered thoroughly and where appropriate these phases may have an impact on the design, certainly on certain details of the design (fig. 7).

Fig. 7. Node of a jacket structure with provisions for offshore lifting.

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3. Bottom founded Compliant Towers in deeper water In water depths exceeding 200 to 300 m oil and gas production is generally achieved by using floating platforms (fig. 8). When operating considerations lead to the wish of developing reservoirs in deeper water using a bottom founded platform rather than a floating platform a so called Compliant Tower may be a cost effective solution in water depths up to some 500m. Designing a conventional Fixed Platform with a relatively low first natural period for a large topsides mass in combination with deep water will lead to an extremely costly solution in view of the amount of structural steel required for the substructure to be stiff enough provided it would be possible to fabricate, transport and /or install such a structure in the first place.

Fig. 8. Typical example of a floating – semi submersible- platform.

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When looking at the envelope of the wave spectra applicable at the location of interest (fig. 9) it can be seen that the aim for conventional fixed platforms is to ensure the natural period to be outside the frequency range of significant wave excitation by designing the jacket to be adequately stiff. The basic design principle of a Compliant Tower is to arrive at a first natural period of the structure high enough to be located on the other side of the peak in the wave spectrum envelope (fig. 10). This can be obtained by finding the right balance between topside mass, stiffness of the substructure and the water depth.

Fig. 9. First natural period of fixed platform in relation to wave spectrum.

Fig. 10. First and second natural period of compliant platform in relation to wave spectrum.

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A typical example of a Compliant Tower is shown in fig. 11 where it can be seen that the flexibility requirement results in a very slender structure which may have an associated highest natural period in excess of 30 second. To obtain a sufficiently high natural period is quite a challenge for the designer, but the problem becomes even more interesting since the second natural period of the structure should also be well outside the peak in the spectrum, generally being less than 5 to 6 seconds, depending on the applicable offshore environment (fig.10). When looking at the first natural period of the structure the designer has to accommodate the required topsides mass and the water depth at the envisaged site. What remains for her or him is the stiffness of the supporting structure.

Fig. 11. Typical example of a compliant tower.

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We are now faced with two important requirements: firstly, the structure should be strong enough to cope with the maximum extreme loading case, a quasi static requirement. Secondly, the structure is also required to have the adequate flexibility to ensure its capability to resist the shorter waves by inertia rather than by stiffness. Generally this strength and stiffness requirements lead the designer to look for additional means to ensure sufficient flexibility without sacrificing strength. A way to increase the flexibility of the tower is not to fix the foundation piles to the base of the structure but have them extending upwards parallel to the tower only to be connected to the tower at a higher elevation; this can be a few hundred meters. This measure results in the vertical reaction forces of the foundation being transferred at a higher elevation causing the tower to be supported by softer vertical springs than would be the case when connected at the base. Clearly also the bending moments in the tower are being influenced by this contrary to the shear forces which always have to be transferred by the braces (fig. 12).

Fig. 12. Influence of the level of the pile-tower connection on the tower's behavior.

It goes without saying that this type of design approach has only been made possible due to the improved quality of materials and welding, due to the advanced calculation tools and knowledge of fatigue behavior and due to the capabilities of the industry to fabricate, transport and install

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this type of structures. The latter requires a significant amount of advanced engineering to ensure the structure is capable to withstand all the relevant stages ranging from fabrication to final installation (fig. 13-15).

Fig. 13. Preparation for launching the compliant tower.

Fig. 14. Compliant tower sliding from the barge.

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Fig. 15. Compliant tower just before leaving the barge.

4 Fixed Platform as an alternative to a Compliant Tower ? As has been shown, the elegance of a Compliant Tower brings along a relatively complex installation procedure which in turn adds to the cost and total installation time of the structure. When taking a closer look at the design of a Compliant Tower that has most recently been installed off the coast of West Africa it appears that the great majority of wave loading is coming from the same direction (fig. 16). This raises the question whether or not it would be possible to design a bottom founded Fixed Structure at that particular location considering this unidirectional wave climate. The installation of such a structure in one piece is feasible by means of launching and the foundation piles can be driven and connected to the structure in the conventional manner resulting in significant time and cost savings. Whether or not the total installed cost of such a substructure will be competitive and will thus totally depend on its cost to fabricate which is mainly determined by its weight. Given the earlier mentioned unidirectional wave climate a Fixed Structure (jacket) should have adequate stiffness in this direction to guarantee a sufficiently low natural period estimated to be approximately 6 seconds for this particular offshore site.

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Can a conventional jacket be designed such that it: 1. has the required stiffness in the direction of maximum dynamic wave excitation, 2. is capable to withstand the maximum quasi static loading, 3. requires an amount of steel equal to or less than the Compliant Tower designed for the same conditions ? To answer the above question a study has been carried out to design and optimize a jacket configuration meeting the design criteria as used for the Compliant Tower.

Fig. 16 Unidirectional wave loading on structure in West Africa.

4.1. Substructure optimization To investigate the possibility of a substructure (jacket) to cope with the environmental conditions at the site of interest the influence of geometrical properties - like base dimensions, number of legs, bracing configuration, member dimensions, number and size of piles, etc.- on the natural periods of the structure and the associated material use has been investigated [1].

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4.2. Bottom layout of the jacket structure The stiffness of the jacket structure largely depends on the dimensions of the base.

normalised required axial pile force [MN/MN]

For highly unidirectional loading the base length and base width can be chosen such that the reaction forces (pile loads) are being optimized. Assuming the foundation piles being located at the corners of the jacket and given the environmental conditions at the site of interest, an optimal base configuration in terms of quasi static pile loading has been found to be approx. 1.5 ( fig. 17).

1,2

1,1

1,0

0,9 0,5

1

1,5

2

2,5

3

3,5

4

4,5

5

Base length / Base w idth ratio [m/m]

Fig. 17 Normalized pile force for a constant base area and different base length / base width ratios.

4.3. Layout of the top of the jacket structure The center to center leg distances at the top of the jacket have initially been assumed to be the same as at the top of the reference compliant tower. 4.4. Member layout of the jacket structure The legs have to withstand two main types of loading: the permanent and variable vertical load caused by the mass of the jacket and topsides and the overturning moment caused by environmental actions. The braces are loaded by the corresponding horizontal forces. Regarding the initial dimensions of the leg and brace members (fig. 18), the following ratios can be applied based on practical experience:

Abrace = 0.1 − 0.2 Aleg

d brace d = 0.03 brace = 40 lbrace tbrace

d leg tleg

= 24

(1)

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For design considerations as well as construction reasons an angle of 30o < θbrace < 60o should be applied.

Fig. 18. Member layout for a single bay.

From these initial dimensions an estimate of the material use can be made. As an example, using a leg diameter of 3.0m and varying the number of vertical members in a single plane (shown for 4 in fig. 18) the resulting steel mass per unit height can be determined as shown in fig. 19.

Fig. 19. Mass structural steel per unit height.

As shown in fig. 19, for a bay width of 70m a configuration with 3 vertical members results in a minimum of material used (the use of 2 vertical members is not meeting the relevant criteria at this bay width). 4.5. Natural period of the jacket structure The flexibility of the structure largely influences its first natural period. In general, a jacket in shallow water has a low natural period compared to the peak of the wave energy spectrum. As a result they experience a relatively low dynamic amplification of the wave forces due to the absence of resonance effects. For a deep water situation the wave force periods may be close to the natural period of the jacket resulting in higher dynamic

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loads which need to be taken into account when considering the fatigue life of the structure. One of the governing parameters in determining the natural periods is the mass of the structure. The topside mass is dictated by functional requirements and the mass of the supporting structure, the jacket, results from its eventual design. The mass of the reference Benguela Belize Compliant Tower is shown in table 1. Table 1 Mass of the reference structure related to the dynamic behavior. Part

Self-weight [mton]

Equivalent topsides mass

45.000

Jacket mass

50.000

Hydrodynamic mass

50.000

Entrapped mass

15.000

Conductors

20.000

As the centre of gravity of the topsides mass is located 26 m above the top of the jacket, an equivalent mass which results in similar dynamic behavior should be used. The equivalent mass is defined by considering the following approach, see fig. 20.

⎛ u + Δ ⋅ θ1 ⎞ M eq = ⎜ 1 ⎟⋅M u1 ⎝ ⎠

(2)

Fig. 20 Lower bound determination of equivalent mass; topsides assumed infinitely stiff.

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For a first estimate of the first natural period of the alternative jacket structure (excl. the foundation flexibility) its behavior is assumed to be determined by a bending mode and a shear mode. For both modes, the natural period can be estimated by the application of the Rayleigh method. Subsequently, the natural period is obtained by

2 2 2 Ttotal ; jacket = Tshear + Tbending

(3)

The effect of varying base dimensions (excl. foundation flexibility) on the first natural period is presented in table 2. Table 2 Natural period estimates for different base dimensions, excluding the foundation flexibility. y - direction

x - direction

Base dimension

[m]

80

87

95

110

120

130

Tjacket (lower bound stiffness)

[s]

8.7

7.9

7.3

6.7

6.5

6.2

Tjacket (upper bound stiffness)

[s]

6.8

6.4

6.1

6.2

6.0

5.7

In table 2 a lower bound based on an analysis of the 4 corner legs participating and an upper bound based on all verticals participating is given. The natural period should be in-between the estimations made for these two cases. The stiffness reducing effects of the foundation will increase the natural period of 5 – 35%. As frequently occurring waves have a period of about 7s – 8s, the natural period of the jacket structure should preferably be lower than 6s, which means a minimum base length in the x-direction of 120 m. 4.6.

Design of a jacket with a base area of 120 m by 95 m

The jacket configuration is shown in fig. 21. For the broad side of the jacket a symmetric bracing pattern is desirable to ensure a balanced transfer of the jacket mass to the barge during transportation and launching. This resulted in a K-bracing for the outer part and an X-bracing for the centre part of this frame.

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Fig. 21 Jacket view in x- and y-direction.

From the model as shown a finite element model has been made to be used in the program SACS. For the jacket structure the wave and current loading incl. their time percentage of occurrence and the foundation stiffness parameters (lateral as well as axial) have been estimated and the natural periods been determined. Also, a fatigue life assessment based on the API recommendations has been carried out. The natural periods as obtained by the computer analyses are shown in table 3. Table 3 Natural periods of the jacket structure with and without foundation flexibilities. SACS model; Tjacket

y - direction

x - direction

Without foundation flexibilities

[s]

5.4

6.5

With foundation flexibilities

[s]

7.6

8.7

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Because of the preliminary requirement of the first natural period being lower than 6s, it is concluded that the total structure is too slender. Therefore, a parameter study is performed in order to meet the natural period criterion at a minimal material use. The main parameters which have been varied are: base dimensions, foundation parameters, dimensions of the legs of the jacket and topside payload. The first three parameters are intended to improve the dynamic behavior or to improve the efficiency of the structure regarding the magnitude of the natural period and the associated material mass. 4.6.1.

Fatigue assessment

Regarding the fatigue assessment, as illustrated by fig. 22, the fatigue damage increases linearly with the natural period of the structure in xdirection when this period exceeds the value of 5.8s. The fatigue damage caused by loads in y-direction seems to be very low compared to the xdirection; clearly due to the unidirectional wave climate.

Fig. 22 Influence of the natural period on fatigue damage for the x-direction, when incorporating wave directionality, dynamic amplification and using the API X’ Wöhler curve.

4.6.2.

Varying the base plan dimensions

The rotational stiffness of the foundation and the bending stiffness of the jacket are strongly influenced by the base dimensions of the structure. The effects of different base lengths on the natural period and the material requirement is shown in table 4. A maximum base length of 140m is being proposed, which is 10m larger than the base length of the largest jacket ever transported.

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Table 4 Effects of different base length on natural period and material requirement (compared to the 120 m base case). Tx

Tjacket;x

Tfoundation;x

Material requirement

[s]

[s]

[s]

[mton]

110

8.0

5.7

5.6

-750

130

7.3

5.1

5.2

+750

140

7.0

4.9

5.0

+1.500

Base length

4.6.3.

Varying foundation properties

A large number of parameters influence the stiffness of the foundation, like: pile wall thickness, number of piles, position of piles, penetration depth and the batter of the piles. Some main conclusions obtained are:

• in terms of material use an increase of the number of piles is more effective than increasing the wall thickness; this requires more installation time, however • increasing the number of piles to an amount larger than 20 reduces the effectiveness of this measure, so a number of 20 seems to be a practical upper limit • applying battered piles seems a rather effective solution; the installation of these piles is relatively complex when compared to installation of vertical piles. 4.6.4.

Varying the leg area

The third major contributor to the stiffness of the structure, apart from the foundation stiffness and the base dimensions, is the steel area of the legs. The base case of the parameter study has a ratio of Abrace / Aleg = 0.10, which is a lower bound. The upper range Abrace / Aleg = 0.25 is about the minimum value to withstand the permanent load of the structure. Table 5 Effects of leg area on natural period and material requirement.

Abrace/Aleg

Tx

Tjacket;x

Tfoundation;x

Material requirement

[s]

[s]

[s]

[mton]

0.10

5.7

4.9

3.0

-

0.15

6.0

5.3

2.8

-6.500

0.20

6.3

5.7

2.8

-10.000

0.25

6.9

6.4

2.7

-12.800

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4.6.5.

Varying topside mass

Although the variation of this parameter is inconsistent with a main functional requirement, the effect of this parameter is considered. Removing some parts of the topsides and placing these parts on for instance a floating structure might be an economical solution. An upper bound estimate can be made for the effects of a topsides mass reduction by considering the total structure as a single-degree-of-freedom system with a weightless beam and a lumped top mass. The variation of the natural period is then related to the square root of the variation of the topsides mass. A reduction of the topside mass by 5.000 mton results into a decrease of natural period of 6%. For a reduction of 10.000 mton, the natural period decreases by 13%. As the effects on the natural period of the key parameters are known, the base can be modified such that a lower natural period is achieved with a relatively low amount of material. Since the relation between the jacket mass and the natural period is known, also the relation between the normalized fatigue damage and the mass of the structure can be estimated, see fig. 23.

Fig. 23 Optimized structural mass of the jacket versus the natural period and the fatigue damage.

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4.7 Comparing the economics of the compliant tower and the proposed jacket structure 4.7.1. Transportation Transport of the compliant tower has been carried out in nine phases; five separate transports of topsides components, three for the main sections of the tower and one transport for the foundation template and piles. The total transportation costs of the Benguela Belize compliant tower was approximately $ 19 million USD. The estimated transportation cost for a single piece jacket and foundation piles is estimated to be $ 16.5 million USD resulting in a reduction in transportation costs of roughly USD 2.5 million. 4.7.2. Installation Regarding the installation of the topsides, the difference in cost for the two types of structures is assumed to be negligible. Installation of the substructure of the compliant tower has been carried out in 4 major phases, which can be reduced to 2 in case of a single piece jacket. Only the launching from a barge and positioning on the seabed is required followed by the pile installation. Result of this shorter installation scenario is an estimated reduction in installation costs of USD 2.0 million. 4.7.3.

Fabrication

Table 6 shows a summary of the fabrication costs of the compliant tower. Table 6 Fabrication costs of the compliant tower. Quantity

Unit

Total

price

[million USD]

Tower

30.500 [mton]

$ 6.875

$ 210

Piling

10.800 [mton]

$ 3.250

$ 35

Temporary ballast tank

900 [mton]

$ 6.875

$6

Fabrication specific complex parts

4% of fabrication costs

Total

$8 $ 259

Based on the total mass of the compliant tower the mass of a competitive jacket should be less than 33.000 mton, which will probably result in a structure with a first natural period its stiff direction of approx. 6.2s.

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5. Conclusions The following conclusions can be drawn when comparing the proposed jacket design with the compliant tower:

• West-African environmental conditions are rather unidirectional, which makes a jacket design with a stiff and a relatively flexible orthogonal direction economically attractive. • A first natural period of a jacket structure of approximately 6.3s does not result in serious fatigue problems when positioned in benign deepwater areas with a strong wave directionality. • The jacket structure as designed is considered to break even with the compliant tower when considering the integral costs and taking into account 10% contingency on the main structural steel of the jacket. Many conservative assumptions have been made during the initial jacket design and the structure is not fully optimized, however. An optimized jacket structure is therefore very likely to have lower integral costs than a compliant tower. • Since the total material use of the compliant tower and jacket designs are almost equal, an increase or decrease in material costs will not significantly influence the previous conclusion. • For the unidirectional benign sea states as applicable in this study it has been concluded that the application of a jacket is even feasible with a slightly larger topsides mass or water depth than was the case for the reference compliant tower.

References [1] MSc-thesis report “Application of a jacket substructure for offshore platforms in benign deepwater areas”. Ir. M.C. Veldhuizen.

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Delft Science in Design 2 M. Eekhout et al. (Eds.) IOS Press, 2008 © 2008 IOS Press and the authors. All rights reserved.

Soft Mobility Products the Experiences of the Delft Design Institute Han Brezet1, Satish Beella2 1

Professor, Design for Sustainability, Industrial Design Engineering, TU Delft, the Netherlands 2 PhD Researcher, Delft Design Institute, Industrial Design Engineering, TU Delft, the Netherlands Abstract Design oriented faculties of the TU Delft today partly gain new knowledge by advanced product development, next to regular research. The “Research by Design” approach enables the answering of research questions that otherwise would be difficult to deal with: in addition to disciplinary problem solution and simulation models, the integration of multiple elements in an advanced, real product design indicates if and under what circumstances user benefits can be realized. The role of the industrial designer consists here in fostering the transition of the potentialities of new principles and technologies to superior product functionalities. In the SoftMob program of the Delft Design Institute and the section Design for Sustainability of the Faculty of Industrial Design Engineering, this approach is being applied on problems and opportunities in the transport area. Particularly, the question has been raised (1) if and how new inter-modal, soft mobility product concepts can contribute to more sustainable transport systems of the future; and (2) how these concepts could be embedded in economically sound service systems. The paper describes the background of the SoftMob program as well as the lessons learnt from quite a number of previous studies and designs. From market research it was found that an emerging need exists from commuters for a small portable device, like the folding bike, but with more comfort and auto-propulsion. Therefore, the Link concept has been developed, a foldable small scooter ready for electrical assistance and/or an advanced battery system or a small hydrogen fuel cell. In order to be able to build the Link, extensive studies had to be undertaken in the areas of novel materials, fuel cells, new battery development, energy management etc. Furthermore, a network of companies, design practitioners and experts has been established. Only via the design of a prototype the research question could be answered if and how these new technologies and principles could be integrated in a product with superior characteristics. Although further testing is needed and niche experiments should give more definite answers, Link is considered to be a feasible and attractive new concept.

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Implementation is foreseen in Friesland, where the conditions for introduction of Link in a future, sustainable transport system are favourable. Besides, the project fostered the knowledge building on new materials, emerging energy technologies and comfort. By systematically applying a variety of industrial design methods and tools, additional valuable new insights on development methodology could be gained. The positive experiences with the SoftMob program and the Link concept in particular have confirmed the Delft Design Institute and the Design for Sustainability program’ management decision to continue their parallel research and design quest aimed at deepening and integrating design knowledge and creating solutions for societal –sustainable mobility- problems at the same time. Keywords: soft mobility, research by design product design, product service systems, fuel cells

1. Introduction Within the Faculty of Industrial Design Engineering (IDE), the Delft Design Institute (DDI) aims at a scientific contribution to product innovation by building complex prototypes and creating related niche experiments. An important ambition of the IDE Faculty research program is to foster the success rate of novel product development in relation to the demands of society, now and in the future. During recent years it has been acknowledged that so many aspects are relevant in this regard, like future contexts, user orientation, ergonomics, aesthetics, materialization, and construction etc. that the risk occurs of sub-optimization: in some areas the IDE Faculty acquires extensive knowledge, while other areas would be underdeveloped. As a consequence, methodologies and guidelines for appropriate product development might appear to be partly unsatisfactory in business practice. In addition, nowadays so many new product technologies1 emerge, like from nano sciences, energy transformation theory and biomedical approaches, that the amount of potentialities for future product functionalities is booming, increasing the complexity of the field. In a global society in which also the speed of -and the time to- the market is more and more decisive for success, this requires additional inputs from technical universities. In order to enable “consistent brilliant innovation”, Larsson and Feland et all [11] argue that we need a new, comprehensive design engineering approach that supports engineers’ capabilities in transitioning new technologies from R&D centers into product architectures. 1

Product technologies are defined here as the entities realizing product

functions [20] 168

One of the responses to this challenge from universities, and the IDE Faculty in Delft in particular, is to create explicit possibilities for experiments with advanced product prototyping, testing and evaluating, based upon new principles, technologies and/or methodologies. In this way, not only research questions, dealing with an integral development approach, can be answered by –potentially- solving all problems by a real product design (“Research by Design”), but at the same time attempts are being made in demonstrating far reaching solutions for societal problems. These potential solutions not only consist of the prototypes and the answers they give to scientific questions and challenges from society, but also in the development of design methods and tools that can help designers to systematically apply gained knowledge in future development processes. To a large extent, the activities in the DDI Institute are being performed by PhD candidates and MSc graduate students, guided by teams of research professors and design practitioners.

Fig. 1 An overview of the DDI approach

The DDI organizes it’s research and design program in close connection with large and small industries, with design consultants and experts and of course with the research groups and programmes of the IDE Faculty. The activities are concentrated around the two following themes:

•

Health & Care

•

Mobility and Energy.

One of the research groups that have joined the DDI program is the Design for Sustainability (DfS) section.

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The DfS program of the Faculty of Industrial Design Engineering aims at contributing to sustainable development by designing advanced artefacts and services with superior life cycle characteristics [10]. The focus of today’s research and design program is on renewable energy (photo voltaics, human power) for portable products and mobility systems, renewable materials (cork, bamboo) for high-end applications and on sustainable product innovation in a global c.q. international context. In cooperation with the DDI, within the SoftMob program a series of new concepts for soft mobility are being developed and tested, as potential enabling elements in tomorrow’s sustainable transport system.

2. Goal, scope and history of the SoftMob program 2.1 Goal Goal of the SoftMob program is to develop scientific knowledge and know how for product-service design based solutions for today’s and future mobility problems, by (1) prototyping, demonstrating, experimenting and evaluating advanced –soft2- mobility products; (2) integrating existing disciplinary product development knowledge from IDE’s Faculty and external knowledge sources and (3) focussing on solutions that potentially contribute to the transition to sustainable societal systems. 2.2 Scope The scope of the program is on new personal transport means that are soft by nature, i.c. that can replace car use, while optimizing sustainability, comfort and other functionalities as well as profiting from the potentialities of new energy technologies. Advanced “bike-up” design solutions are the point of departure of the activities, including future context and use research, the creation of concepts, product prototyping and testing in experimental markets.

2 The attribute “soft” points here at those person and goods’ transport modes and chains –such as inter-modal, waterborne, rail, other public transport, human powered etc.- that in most circumstances are more sustainable than motorised individual mobility. It can also include traditional transport modes with a breakthrough in terms of performance and energy efficiency. 170

3. The SoftMob program The search of alternatives for urban car transport is one of the starting points of DfS chain mobility program, as can be seen in figure 2. It went through several iterations within the DfS program, before entering the joint venture with the DDI Institute.

Fig. 2 Chain mobility program

Short distance mobility in urban areas is one of the problem areas in the Netherlands. Most commuters use their bike for a maximum home-work distance up to 5-10 km. A study [4] carried out at sports’ company Nike headquarters in Hilversum revealed that lack of comfort was one of the mean reasons for avoiding a wider range. Therefore, a trajectory was set in motion, in close cooperation with the Nike, Gazelle bicycle company, TNO/Kathalys, van der Veer designers, Freewheel and others, to create an attractive and comfortable solution for short distance commuting (1020 km home-work distance). The aim was to find an attractive alternative for the urban car use at wider distances. After extensive studies and surveys, a prototype of MITKA was realised (see Figure 3) including a help motor for pedalling, novel seat position, three-wheel architecture and a tilting steering mechanism in the front. The idea was to build a full test series for demonstration by Nike’s employee’s in their daily commuting.

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Fig. 3 Mitka, alternative for urban car transport

However, due to both technical, design and managerial reasons the MITKA never exploited the prototype stage. The three-wheel vehicle was very comfortable for the user, but too big to manoeuvre on small bicycle roads and too slow for the main road. Moreover, it’s features were considered to be too expensive for a huge market, keeping investors and business implementation away. Although novel elements of MITKA, such as the seat, found their way to the market, no possibilities emerged to test other essential elements of the new mobility concept, such as financial services, maintenance and repair services, health benefits etc. However for the SoftMob program, several lessons for future design could be learnt from the MITKA project [4]:

• Radical design projects -with a high environmental ambitionshould preferably apply a bricolage approach, including a flexible versus an ideological vision, capacity building via ready-to-use experimentation and a series of small incremental steps rather than one big jump. In this way technological risks can be reduced. • From a business perspective, at least three questions should be answered at the start of a Soft Mob project: “what is our business?”, “who is the customer?” and “what is the customer value?” Parallel to MITKA, several other alternatives were explored that could lead to reduction in car use, either for commuting or in tourism and recreation. Some of these studies were focussing on artefacts, others more on

172

service and infrastructure solutions, in line with the study of Mont [19], indicating that an integrated combination of novel products, services, infrastructure and organization is a precondition for sustainable solutions at system level.

Fig. 4 Overview of design studies aimed at alternatives for car

Maas [17] and Koenderink [15] found several new options for comfort, including novel options for weather protection and aerodynamic design, while van der Woning [22] focussed on the opportunities of new materials for a light weight – one size fits all bike concept. Cordozo [8] studied the possibility of a mix between a robust city bike and a handy foldable device: with the design of the foldable bike he demonstrated that with minimal elements a portable, comfortable and multifunctional bike concept is feasible. While aforementioned studies focussed on the soft mobility artefacts, others studied the service and infrastructure context. Worm [23] found several options to stimulate sustainable chain mobility, such as ‘Fietsdubble’, ‘Fietsforward’ and ‘cybervoertuigen’, etc. Iraci [14] and Boelens [7] sketched today’s and future opportunities for superior chain mobility systems, and particularly the role of advanced bikes and information and communication technology, to foster easy transition for the user from one type of mobility (train, bus etc.) to others (bike etc.) and vice versa. They concluded that the need exists to foresee the whole service system, than to develop the system itself and customize the

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artefact accordingly. Along the same line, van de Goot [12] stresses the importance of an appropriate physical and informational infrastructure to enable sustainable chain mobility solutions.

4. Today’s SoftMob program From the previous studies, several conclusions for the roadmap of the SoftMob program can be drawn. The most important are:

• Design demonstration: The general product design is seen as combination of disciplines of form-giving, engineering, ergonomics and innovation management. The product needs to demonstrate the optimal combination of these disciplines for intended purpose and market. Product development and demonstration gives more opportunities for integral testing and for improvement of the market worthiness of artefacts; •

Need for advanced concepts: The finding is also that there is a pressing need for advanced concepts which could be using advanced technologies and materials to overcome the issues with traditional technologies. The application of advanced technologies for functionalities like light-weight commuting and inter-modal chain mobility options;

•

Expertise in the field: The cooperation of knowledge institutes and companies in the initial stages of product development gives the practitioners help and reflection from policy, design, market feasibility and engineering;

• Sustainability and system perspective: Available knowledge on sustainable mobility at faculty IDE in the form of experts and previous projects could be a head start in coming forward with more practical solutions. The system perspective is aimed at the enabling of a particular function (e.g., door to door) and not at just bringing another product on the market. The combination of the sustainable perspective and system thinking should result in a more complete solution; • The scope of the program is mainly based on soft mobility designs, chain mobility options, product-service systems and sustainable urban infrastructure. The DDI design activities that are undertaken by researchers and students, in cooperation with the DDI external partners, are the basis of the program. At the same time the designer-researcher team will describe, analyze, assess and reflect upon the progress made, specifically from the perspective of the research questions. This also includes the development of a framework and -living- program of requirements for design evaluation and optimization. In this program it is also proposed

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that research will follow a reflective-practice approach. The coexistence of design and research cycles need to be further clarified in the research trajectory. 4.1 Advanced Mobility Within the project several studies on the future of mobility systems and users’ needs have been undertaken, leading to a scope on small, foldable concepts for short distance commuting. The assumptions and research findings are summarized as below:

• Portable and light vehicles could be solutions for the transport of people and their luggage in specific markets and certain niche circumstances (where a quick, clean and individual transfer over a limited number of kilometres is required). • In inter-modal situations, like commuting and tourist trips, the concept should be easily distributed, handled and stored as own personal luggage.

• Battery and fuel cell technologies, as alternative energy systems, offer the potential of significantly decreasing local carbon dioxide emissions. After extensive benchmark studies [1], idea finding and the creation of a number of design concepts, the elaboration of one of them has been chosen: the “Link” concept. The Link is a foldable vehicle (close to a moped) that can be brought as luggage in public transport or in a car trunk, and is used as before- and after-transport. The Link is designed to be powered by advanced batteries, high-capacitors and/or in combination with a fuel cell. Among other advantages Link adds as functionality that it can be driven seated as well as standing: changing between these modes can be performed easily by folding the saddle bar. 4.2 Role of artefact design and services In close connection to the design of the actual artefact and an accurate description and analysis of the design process, several research questions emerge. Particularly, the PhD study of Beella [3] focuses on the following main research questions: How to foster innovation by integration of emerging new technologies and